mailbox: Add snapshot of MSM QMP driver

This is a snapshot of the MSM QMP driver taken of msm-4.9 commit
<ea5c48deabd8> (Merge "msm: sde: avoid request dereference with cached
sequence id").

In addition, remove dependency on MSM_SMEM from KConfig.

Change-Id: I465e09a7d49d808d0388d2795db2fcfb577b1514
Signed-off-by: Chris Lew <clew@codeaurora.org>