vknulldrv: Change module name to not clash with real drivers

Change-Id: I3135943894f83fd906c6835552ec93ea5f7c7dfe
(cherry picked from commit 2b000b984027932679cc6aa145fc11e9ef1b11fa)
diff --git a/vulkan/nulldrv/Android.mk b/vulkan/nulldrv/Android.mk
index b98ec20..2db6138 100644
--- a/vulkan/nulldrv/Android.mk
+++ b/vulkan/nulldrv/Android.mk
@@ -35,7 +35,8 @@
 
 LOCAL_SHARED_LIBRARIES := liblog
 
-LOCAL_MODULE := vulkan.$(TARGET_BOARD_PLATFORM)
+# Real drivers would set this to vulkan.$(TARGET_BOARD_PLATFORM)
+LOCAL_MODULE := vulkan.default
 LOCAL_PROPRIETARY_MODULE := true
 LOCAL_MODULE_RELATIVE_PATH := hw
 LOCAL_MODULE_TAGS := optional