use 4.2.4 for ARC by default

target/config/Config.in.kernelversion

@@ -4,6 +4,7 @@
 choice
 prompt "Kernel Version"
 depends on ADK_TARGET_KERNEL_CUSTOMISING
+default ADK_TARGET_KERNEL_VERSION_4_2_4 if ADK_TARGET_ARCH_ARC
 default ADK_TARGET_KERNEL_VERSION_4_1_10
 
 config ADK_TARGET_KERNEL_VERSION_GIT