firmware: arm_scmi: Fix sparse warnings in OPTEE transport driver

The sparse checker complains about converting pointers between address
spaces.  We correctly stored an __iomem pointer in struct scmi_optee_channel,
but discarded the __iomem when returning it from get_channel_shm, causing one
warning. Then we passed the non-__iomem pointer return from get_channel_shm
at two other places, where an __iomem pointer is expected, causing couple of
other warnings

Add the appropriate __iomem annotations at all places where it is missing.

optee.c:414:20: warning: incorrect type in return expression (different address spaces)
optee.c:414:20:    expected struct scmi_shared_mem *
optee.c:414:20:    got struct scmi_shared_mem [noderef] __iomem *shmem
optee.c:426:26: warning: incorrect type in argument 1 (different address spaces)
optee.c:426:26:    expected struct scmi_shared_mem [noderef] __iomem *shmem
optee.c:426:26:    got struct scmi_shared_mem *shmem
optee.c:441:30: warning: incorrect type in argument 1 (different address spaces)
optee.c:441:30:    expected struct scmi_shared_mem [noderef] __iomem *shmem
optee.c:441:30:    got struct scmi_shared_mem *shmem

Link: https://lore.kernel.org/r/20220404102419.1159705-1-sudeep.holla@arm.com
Cc: Etienne Carriere <etienne.carriere@linaro.org>
Cc: Cristian Marussi <cristian.marussi@arm.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/optee.c

@@ -405,8 +405,8 @@ static int scmi_optee_chan_free(int id, void *p, void *data)
 	return 0;
 }
 
-static struct scmi_shared_mem *get_channel_shm(struct scmi_optee_channel *chan,
-					       struct scmi_xfer *xfer)
+static struct scmi_shared_mem __iomem *
+get_channel_shm(struct scmi_optee_channel *chan, struct scmi_xfer *xfer)
 {
 	if (!chan)
 		return NULL;
@@ -419,7 +419,7 @@ static int scmi_optee_send_message(struct scmi_chan_info *cinfo,
 				   struct scmi_xfer *xfer)
 {
 	struct scmi_optee_channel *channel = cinfo->transport_info;
-	struct scmi_shared_mem *shmem = get_channel_shm(channel, xfer);
+	struct scmi_shared_mem __iomem *shmem = get_channel_shm(channel, xfer);
 	int ret;
 
 	mutex_lock(&channel->mu);
@@ -436,7 +436,7 @@ static void scmi_optee_fetch_response(struct scmi_chan_info *cinfo,
 				      struct scmi_xfer *xfer)
 {
 	struct scmi_optee_channel *channel = cinfo->transport_info;
-	struct scmi_shared_mem *shmem = get_channel_shm(channel, xfer);
+	struct scmi_shared_mem __iomem *shmem = get_channel_shm(channel, xfer);
 
 	shmem_fetch_response(shmem, xfer);
 }