GKI cleanup - Replaced usage of GKI queue with OSI fixed_queue

* Added new functions to OSI:
  - fixed_queue_init()
  - fixed_queue_length()
  - fixed_queue_try_remove_from_queue()
  - fixed_queue_try_peek_last()

* Renamed fixed_queue_try_peek() to fixed_queue_try_peek_first()

* Replaced usage of GKI queue functions with OSI fixed_queue functions:
  - GKI_init_q() -> fixed_queue_new(SIZE_MAX)
    NOTE: unlike GKI_init_q(), fixed_queue_new() allocates memory /
    state that needs to be released by calling fixed_queue_free()
  - GKI_enqueue() -> fixed_queue_enqueue()
  - GKI_dequeue() -> fixed_queue_try_dequeue()
    NOTE: fixed_queue_try_dequeue() is non-blocking
  - GKI_queue_length() -> fixed_queue_length()
  - GKI_queue_is_empty() -> fixed_queue_is_empty()
  - GKI_getfirst() -> fixed_queue_try_peek_first()
  - GKI_getlast() -> fixed_queue_try_peek_last()
  - GKI_remove_from_queue() -> fixed_queue_try_remove_from_queue()
  - Queue elements iteration.
    In the fixed_queue implementation we have to use the underlying
    list_t mechanism to iterate over the elements.
    OLD:
      p = GKI_getfirst(queue);
      ...
      while ((p = GKI_getnext(p) != NULL) {
         ...
      }
    NEW:
      list_t *list = fixed_queue_get_list(queue);
      for (const list_node_t *node = list_begin(list);
           node != list_end(list); node = list_next(node)) {
          p = list_node(node);
      }

* Remove initialization of the GKI module, because it is not needed
  anymore

* Removed unused files in GKI:
  gki/common/gki_common.h
  gki/ulinux/gki_int.h
  gki/ulinux/gki_ulinux.c

Change-Id: I3ff9464db75252d6faf7476a9ca67c88e535c51c
diff --git a/stack/btm/btm_acl.c b/stack/btm/btm_acl.c
index c8e0e7b..5eb142a 100644
--- a/stack/btm/btm_acl.c
+++ b/stack/btm/btm_acl.c
@@ -2394,7 +2394,7 @@
     BD_ADDR bda;
     BTM_TRACE_DEBUG ("btm_acl_resubmit_page");
     /* If there were other page request schedule can start the next one */
-    if ((p_buf = (BT_HDR *)GKI_dequeue (&btm_cb.page_queue)) != NULL)
+    if ((p_buf = (BT_HDR *)fixed_queue_try_dequeue(btm_cb.page_queue)) != NULL)
     {
         /* skip 3 (2 bytes opcode and 1 byte len) to get to the bd_addr
          * for both create_conn and rmt_name */
@@ -2425,8 +2425,8 @@
     BT_HDR *p;
     BTM_TRACE_DEBUG ("btm_acl_reset_paging");
     /* If we sent reset we are definitely not paging any more */
-    while ((p = (BT_HDR *)GKI_dequeue(&btm_cb.page_queue)) != NULL)
-        GKI_freebuf (p);
+    while ((p = (BT_HDR *)fixed_queue_try_dequeue(btm_cb.page_queue)) != NULL)
+        GKI_freebuf(p);
 
     btm_cb.paging = FALSE;
 }
@@ -2448,7 +2448,7 @@
     if (btm_cb.discing)
     {
         btm_cb.paging = TRUE;
-        GKI_enqueue (&btm_cb.page_queue, p);
+        fixed_queue_enqueue(btm_cb.page_queue, p);
     }
     else
     {
@@ -2462,7 +2462,7 @@
             if (btm_cb.paging &&
                 memcmp (bda, btm_cb.connecting_bda, BD_ADDR_LEN) != 0)
             {
-                GKI_enqueue (&btm_cb.page_queue, p);
+                fixed_queue_enqueue(btm_cb.page_queue, p);
             }
             else
             {