Enable DRM HIDL HAL by default

Eliminate ENABLE_TREBLE since it is obsolete.
Switching back to legacy DRM is still possible
by building with DISABLE_TREBLE_DRM=true

Change-Id: I6b921050dff6162112c60df21549fc93bc46e379
diff --git a/services/mediadrm/Android.mk b/services/mediadrm/Android.mk
index 2bf2201..e72236d 100644
--- a/services/mediadrm/Android.mk
+++ b/services/mediadrm/Android.mk
@@ -25,7 +25,7 @@
     liblog \
     libmediadrm \
     libutils
-ifeq ($(ENABLE_TREBLE), true)
+ifneq ($(DISABLE_TREBLE_DRM), true)
 LOCAL_SHARED_LIBRARIES += \
     libhidlbase \
     libhidlmemory \
@@ -34,8 +34,8 @@
 endif
 
 LOCAL_CFLAGS += -Wall -Wextra -Werror
-ifeq ($(ENABLE_TREBLE), true)
-LOCAL_CFLAGS += -DENABLE_TREBLE=1
+ifeq ($(DISABLE_TREBLE_DRM), true)
+LOCAL_CFLAGS += -DDISABLE_TREBLE_DRM=1
 endif
 
 LOCAL_MODULE:= mediadrmserver