Use combined kernel prebuilt device/google/redbull-kernel for bramble/redfin

Bug: 162558931
Change-Id: I6f858e7da74ee99b9014cdfe6b37c60523d9474a
diff --git a/BoardConfig-common.mk b/BoardConfig-common.mk
index d738cd3..c38d4e4 100644
--- a/BoardConfig-common.mk
+++ b/BoardConfig-common.mk
@@ -481,7 +481,7 @@
 TARGET_BOARD_COMMON_PATH := $(TARGET_BOARD_NAME_DIR)/sm7250
 
 # Common kernel file handling
-TARGET_KERNEL_DIR := $(TARGET_BOARD_NAME_DIR:%/=%)-kernel
+TARGET_KERNEL_DIR := device/google/redbull-kernel
 
 # DTBO partition definitions
 ifneq (,$(filter userdebug eng, $(TARGET_BUILD_VARIANT)))