Revert "Update to 4.7 toolchain to match previous config"

This reverts commit 7555e42c789a9ada162cbadcdc8e626b1a81feeb.

Mako kernel should build with 4.6 toolchain
diff --git a/build.config b/build.config
index 17ee5b7..1477596 100644
--- a/build.config
+++ b/build.config
@@ -4,7 +4,7 @@
 DEFCONFIG=mako_defconfig
 EXTRA_CMDS=''
 KERNEL_DIR=private/msm-lge
-LINUX_GCC_CROSS_COMPILE_PREBUILTS_BIN=prebuilts/gcc/linux-x86/arm/arm-eabi-4.7/bin
+LINUX_GCC_CROSS_COMPILE_PREBUILTS_BIN=prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin
 FILES="
 arch/arm/boot/zImage
 vmlinux