camera_metadata: fix metadata clone bug

clone_camera_metadata fails at validation during camera start, then crashes
camera.

Bug: 11879762
Change-Id: I9437c6724dd290aec162ae8b68be898b2f9a5b9e
diff --git a/camera/src/camera_metadata.c b/camera/src/camera_metadata.c
index 4e34ac6..07c3b43 100644
--- a/camera/src/camera_metadata.c
+++ b/camera/src/camera_metadata.c
@@ -186,7 +186,6 @@
 
 camera_metadata_t *allocate_camera_metadata(size_t entry_capacity,
                                             size_t data_capacity) {
-    if (entry_capacity == 0) return NULL;
 
     size_t memory_needed = calculate_camera_metadata_size(entry_capacity,
                                                           data_capacity);
@@ -201,7 +200,6 @@
                                          size_t entry_capacity,
                                          size_t data_capacity) {
     if (dst == NULL) return NULL;
-    if (entry_capacity == 0) return NULL;
 
     size_t memory_needed = calculate_camera_metadata_size(entry_capacity,
                                                           data_capacity);
@@ -298,6 +296,7 @@
                                        const size_t *expected_size) {
 
     if (metadata == NULL) {
+        ALOGE("%s: metadata is null!", __FUNCTION__);
         return ERROR;
     }