android: simplify the including rule of subdirs

Use android build system functions to include Android.mk
of subdirs.

Signed-off-by: Chih-Wei Huang <cwhuang@linux.org.tw>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
[Emil Velikov: Resolve trivial conflicts.]
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

Android.mk

@@ -45,13 +45,4 @@ LOCAL_CFLAGS := \
 
 include $(BUILD_SHARED_LIBRARY)
 
-SUBDIRS := \
+include $(call all-makefiles-under,$(LOCAL_PATH))
-	freedreno \
-	intel \
-	nouveau \
-	radeon \
-	libkms \
-	tests/modetest
-
-mkfiles := $(patsubst %,$(LIBDRM_TOP)/%/Android.mk,$(SUBDIRS))
-include $(mkfiles)

tests/Android.mk

@@ -0,0 +1 @@
+include $(call all-subdir-makefiles)