firmware: arm_scmi: Add smc/hvc transport

Use the value of "arm,smc-id" property from the device tree as the first
argument for SMCCC call leaving all the other arguments as zero for now.

There is no Rx, only Tx because of smc/hvc not support Rx.

Link: https://lore.kernel.org/r/1583673879-20714-3-git-send-email-peng.fan@nxp.com


Signed-off-by: Peng Fan <peng.fan@nxp.com>
[sudeep.holla: reworded commit log/subject and fixed !HAVE_ARM_SMCCC build]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>