hikey960.mk: set HIKEY_USES_GKI true for mainline kernel am: ca30a6e803 am: c1c3214384

Original change: https://android-review.googlesource.com/c/device/linaro/hikey/+/2373271

Change-Id: I4e3b1915e6ce89356f6d97f8fa2076a6f2174395
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/hikey960.mk b/hikey960.mk
index 3a58d25..673181c 100644
--- a/hikey960.mk
+++ b/hikey960.mk
@@ -8,6 +8,10 @@
 ifndef HIKEY_USES_GKI
   ifeq ($(TARGET_KERNEL_USE), 5.4)
     HIKEY_USES_GKI := true
+  else
+    ifeq ($(TARGET_KERNEL_USE), mainline)
+      HIKEY_USES_GKI := true
+    endif
   endif
 endif