kbuild: Move CONFIG_STACK_CANARIES check

This patch moves the CONFIG_STACK_CANARIES check from architecture's
Makefile to the root Makefile since this option is kernel-related,
not architecture-related. This way we avoid replicating the same
CONFIG_STACK_CANARIES check in several Makefiles.

This patch also removes some blank lines from the Makefiles it touches.

Change-Id: I458f92fa6799526c608369d1e56579936bcb196e
Signed-off-by: Andre Guedes <andre.guedes@intel.com>