The shared memory buffer allocated by the optee driver is normal cached
memory and can't be used with IOMEM APIs used in shmem_*.

We currently support only IO memory for shared memory and supporting
normal cached memory needs more changes and needs to be thought through
properly. So for now, let us drop the support for this OPTEE shared buffer.

Link: https://lore.kernel.org/r/20211125150730.188487-1-sudeep.holla@arm.com
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>