Add support for TEE shared memory in optee scmi transport. When using
tee shared memory, scmi optee transport manages SCMI messages using
msg protocol(from msg.c) in shared memory, whereas smt(from shmem.c)
protocol is used with static IOMEM based shared buffers.

Link: https://lore.kernel.org/r/20220425085127.2009-1-etienne.carriere@linaro.orgReviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>