use 4.6 for ARC, as it contains a lot of fixes

target/config/Config.in.kernelversion

@@ -5,6 +5,7 @@ choice
 prompt "Kernel version" if !ADK_TARGET_CHOOSE_ARCH
 depends on ADK_TARGET_OS_LINUX
 default ADK_TARGET_KERNEL_VERSION_GIT if ADK_TARGET_WITHOUT_MMU && ADK_TARGET_ARCH_XTENSA
+default ADK_TARGET_KERNEL_VERSION_4_6_0 if ADK_TARGET_ARCH_ARC
 default ADK_TARGET_KERNEL_VERSION_4_4_10
 
 config ADK_TARGET_KERNEL_VERSION_GIT