hikey/hikey960: Remove SF_START_GRAPHICS_ALLOCATOR_SERVICE hack

Alistair pointed out we had the SF_START_GRAPHICS_ALLOCATOR_SERVICE
flag enabled which prevents HIDL allocator from being used.

So remove it to get treble working.

Change-Id: Ifeec58346b230ae8bd87b265c492be61f781d639
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/BoardConfigCommon.mk b/BoardConfigCommon.mk
index 3ab2410..ef4544e 100644
--- a/BoardConfigCommon.mk
+++ b/BoardConfigCommon.mk
@@ -32,7 +32,6 @@
 TARGET_USE_PAN_DISPLAY := true
 
 TARGET_USES_HWC2 := true
-SF_START_GRAPHICS_ALLOCATOR_SERVICE := true
 
 TARGET_AUX_OS_VARIANT_LIST := neonkey argonkey