firmware: arm_scmi: replace of_match_device->data with of_device_get_match_data()
of_match_device can return NULL if no matching device is found though
it's highly unlikely to happen in scmi_probe as it's called only if
a valid match is found.
However we can use of_device_get_match_data() instead of
of_match_device()->data to handle NULL pointer checks and return -EINVAL
in such a scenario.