firmware: arm_scmi: Make use of tee bus methods

firmware: arm_scmi: Make use of tee bus methods

The tee bus got dedicated callbacks for probe and remove.
Make use of these. This fixes a runtime warning about the driver needing
to be converted to the bus methods. Note that the return value of .remove()
was already ignored before, so there is no problem introduced by dropping
the error returns.

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>