Camera: Fix complilation issue for OSS builds.

Added a check to compile libcamera2 only while building for a QC target.
All other times the CameraStub should be compiled.
diff --git a/Android.mk b/Android.mk
index ede9ff1..a3d61cc 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,3 +1,4 @@
+ifeq ($(strip $(BOARD_USES_QCOM_HARDWARE)), true)
 BUILD_LIBCAMERA:=true
 ifeq ($(BUILD_LIBCAMERA),true)
 
@@ -33,3 +34,4 @@
 
 endif # BUILD_TINY_ANDROID
 endif # BUILD_LIBCAMERA
+endif # BOARD_USES_QCOM_HARDWARE