QTI Mailbox Protocol (QMP) is a lightweight communication
driver that fits in to the mailbox framework. Each mailbox
supports up to one channel. This channel can send and receive
one message at a time.
Change-Id: I944d001600c1f0acb8cd602040b90685f80713a7
Signed-off-by: Chris Lew <clew@codeaurora.org>