defconfig: Enable stack protection on 64-bit MSM

Enable stack protection on 64-bit MSM targets.  For now, enable the
"regular" stack protection, which users stack canaries for some cases
of char arrays.  The kernel also supports "strong" stack protection,
which can be enabled once gcc 4.9 is available for a build.

CRs-Fixed: 673518
Change-Id: I36677f7183c7f0650539edec91c25dbd7d0f5135
Signed-off-by: David Brown <davidb@codeaurora.org>