[ARM] msm: shared memory interface for baseband processor ipc

[ARM] msm: shared memory interface for baseband processor ipc

This code provides the low level interface to the "shared memory
state machine" (smsm), and the virtual serial channels (smd), used
to communicate with the baseband processor.  Higher level transports
(rpc, ethernet, AT command channel, etc) ride on top of this.

Signed-off-by: Brian Swetland <swetland@google.com>