kernel.mk: fix clang build if path is set

Change-Id: I37940225d0191d56ced45eff539cc8d1cb9f8a9b
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index 99bba3b..104924f 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -250,7 +250,11 @@
         # Only set the latest version of clang if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config
         KERNEL_CLANG_VERSION := $(shell ls -d $(BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/clang-* | xargs -n 1 basename | tail -1)
     endif
-    TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/$(KERNEL_CLANG_VERSION)/bin
+    ifneq ($(TARGET_KERNEL_CLANG_PATH),)
+        TARGET_KERNEL_CLANG_PATH := $(BUILD_TOP)/$(TARGET_KERNEL_CLANG_PATH)/bin
+    else
+        TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/$(KERNEL_CLANG_VERSION)/bin
+    endif
     ifeq ($(KERNEL_ARCH),arm64)
         KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=aarch64-linux-gnu-
     else ifeq ($(KERNEL_ARCH),arm)