arm: mach-msm: Enable ARCH_WANT_KMAP_ATOMIC_FLUSH for all msm

Enable ARCH_WANT_KMAP_ATOMIC_FLUSH for all targets that
can have high memory. This would ensure that the stale
highmem mappings are flushed when needed, for e.g. while
handing over a buffer for secure use.

CRs-Fixed: 1001061
Change-Id: I51567129f41660f3f8244d2bc6f3f41d4415a779
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>