soong: Set a default for TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS

Devices not setting BOARD_USES_QCOM_HARDWARE to true fail to build
in case a default is not set.

Change-Id: I6643aa08244a5c476a45336485362dd7876fc90c
diff --git a/config/BoardConfigSoong.mk b/config/BoardConfigSoong.mk
index 0ec834d..04caf9d 100644
--- a/config/BoardConfigSoong.mk
+++ b/config/BoardConfigSoong.mk
@@ -74,6 +74,7 @@
 
 # Set default values
 BOOTLOADER_MESSAGE_OFFSET ?= 0
+TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS ?= 0
 TARGET_INIT_VENDOR_LIB ?= vendor_init
 TARGET_SPECIFIC_CAMERA_PARAMETER_LIBRARY ?= libcamera_parameters
 TARGET_SURFACEFLINGER_FOD_LIB ?= surfaceflinger_fod_lib