defconfig: sdxpoorwills: Enable SMMU driver for sdxpoorwills

Enable SMMU driver support for sdxpoorwills. This would
enable IOVA to PA translation support and memory protection
for client devices.

Change-Id: I4a0cf8cf75a3adee2242707d4725e5058540f12c
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>