crackling: Enable secure discard

* This is required per CDD now. A lot of devices disable it because it
   can be absurdly slow (as it is in this case). We'll make sure it's
   only used where necessary.

Change-Id: I636bb78cc6bd920c7c39727a561d3cd835fd975e

BoardConfig.mk

@@ -41,9 +41,6 @@ USE_DEVICE_SPECIFIC_CAMERA := true
 # Crypto
 TARGET_HW_DISK_ENCRYPTION := true
 
-# Flags
-COMMON_GLOBAL_CFLAGS += -DNO_SECURE_DISCARD
-
 # GPS
 USE_DEVICE_SPECIFIC_GPS := true
 TARGET_NO_RPC := true