hal: add -Wno-error=format to compiler flags

Change-Id: I2496a1ee5752d6cc1541db13c8e939643192883d
diff --git a/hal/Android.mk b/hal/Android.mk
index 72fd0ef..e6e69b4 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -309,7 +309,7 @@
 
 LOCAL_VENDOR_MODULE := true
 
-LOCAL_CFLAGS += -Werror
+LOCAL_CFLAGS += -Werror -Wno-error=format
 
 include $(BUILD_SHARED_LIBRARY)