kernel: Use linux-android- toolchains to build kernel on aarch64 and x86

* -androidkernel ones became symlinks to -android ones long time ago, use
   -android executables directly to simplify the logic on these platforms.
 * Keep arm on -androidkernel because it doesn't boot for some reason.

Change-Id: I97dd93121fc0e805a965e3f8b84466dd7bd686c0

config/BoardConfigKernel.mk

@@ -24,8 +24,8 @@
 #   TARGET_KERNEL_ARCH                 = Kernel Arch
 #   TARGET_KERNEL_CROSS_COMPILE_PREFIX = Compiler prefix (e.g. arm-eabi-)
 #                                          defaults to arm-linux-androidkernel- for arm
-#                                                      aarch64-linux-androidkernel- for arm64
-#                                                      x86_64-linux-androidkernel- for x86
+#                                                      aarch64-linux-android- for arm64
+#                                                      x86_64-linux-android- for x86
 #
 #   TARGET_KERNEL_CLANG_COMPILE        = Compile kernel with clang, defaults to false
 #
@@ -56,15 +56,11 @@ TARGET_KERNEL_CROSS_COMPILE_PREFIX := $(strip $(TARGET_KERNEL_CROSS_COMPILE_PREF
 ifneq ($(TARGET_KERNEL_CROSS_COMPILE_PREFIX),)
 KERNEL_TOOLCHAIN_PREFIX ?= $(TARGET_KERNEL_CROSS_COMPILE_PREFIX)
 else ifeq ($(KERNEL_ARCH),arm64)
-ifeq ($(TARGET_KERNEL_CLANG_COMPILE),true)
-    KERNEL_TOOLCHAIN_PREFIX ?= aarch64-linux-android-
-else
-    KERNEL_TOOLCHAIN_PREFIX ?= aarch64-linux-androidkernel-
-endif
+KERNEL_TOOLCHAIN_PREFIX ?= aarch64-linux-android-
 else ifeq ($(KERNEL_ARCH),arm)
 KERNEL_TOOLCHAIN_PREFIX ?= arm-linux-androidkernel-
 else ifeq ($(KERNEL_ARCH),x86)
-KERNEL_TOOLCHAIN_PREFIX ?= x86_64-linux-androidkernel-
+KERNEL_TOOLCHAIN_PREFIX ?= x86_64-linux-android-
 endif
 
 ifeq ($(KERNEL_TOOLCHAIN),)