firmware: arm_scmi: optee: Rework transport probe sequence

firmware: arm_scmi: optee: Rework transport probe sequence

Use the new per-instance transport handles helpers to synchronize and
optionally defer the core SCMI driver probe up until the transport driver
has completely been initialized and it is fully operational as a supplier.

Introduce proper module init/exit routines while removing the ugly trick of
registering a driver from within the probe sequence of another one, just to
avoid to have to deal with probe deferrals.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://patch.msgid.link/20260510160527.3537474-5-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>