firmware: scmi: mailbox: Support arm,max_rx_timeout_ms

firmware: scmi: mailbox: Support arm,max_rx_timeout_ms

Per devicetree bindings:
arm,max-rx-timeout-ms indicates an optional time value, expressed in
milliseconds, representing the transport maximum timeout value for the
receive channel. The value should be a non-zero value if set.

Support this property if platform set it to a non-default value. This
property is a per SCMI property, so all channels share same value.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>