power: Simplify display_hint_sent

Check for whether the display hint has been sent at the start
of the set_interactive() function in the common powerHAL.

This gets rid of the need to replicate the same variable in
every target-specific powerHAL that implements the
set_interactive_override() function.

Also remove the unnecessary saved_interactive_mode variable
used by the msm-dcvs governor; its function is superseded by
the variable display_hint_sent.

Change-Id: If7dd11fcb578211f4f83847f9257232c4138ce53
diff --git a/power-8992.c b/power-8992.c
index c87ba5a..d4b020d 100644
--- a/power-8992.c
+++ b/power-8992.c
@@ -47,8 +47,6 @@
 #include "performance.h"
 #include "power-common.h"
 
-static int display_hint_sent;
-
 static int process_video_encode_hint(void *metadata)
 {
     char governor[80];
@@ -125,18 +123,14 @@
         /* Display off */
         if (is_interactive_governor(governor)) {
             int resource_values[] = {0x777}; /* 4+0 core config in display off */
-            if (!display_hint_sent) {
-                perform_hint_action(DISPLAY_STATE_HINT_ID,
-                resource_values, ARRAY_SIZE(resource_values));
-                display_hint_sent = 1;
-                return HINT_HANDLED;
-            }
+            perform_hint_action(DISPLAY_STATE_HINT_ID,
+                    resource_values, ARRAY_SIZE(resource_values));
+            return HINT_HANDLED;
         }
     } else {
         /* Display on */
         if (is_interactive_governor(governor)) {
             undo_hint_action(DISPLAY_STATE_HINT_ID);
-            display_hint_sent = 0;
             return HINT_HANDLED;
         }
     }