defconfig: arm: Enable missing mmc config flags on sdxpoorwills

Enable mmc config flags for clock gating, deferred resume,
performance profiling on sdxpoorwills. Enable mmc ring buffer only
for debug builds.

Change-Id: I3b48d8e709e4e017d796e5fbe66096781844f9f7
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>