remoteproc: k3: Refactor .unprepare rproc ops into common driver

remoteproc: k3: Refactor .unprepare rproc ops into common driver

The .unprepare rproc ops implementations in TI K3 DSP and M4 remoteproc
drivers assert the module reset on the remote processor. Refactor the
implementations into ti_k3_common.c driver as k3_rproc_unprepare() and
register this common function as .unprepare ops in DSP and M4 drivers.

Signed-off-by: Beleswar Padhi <b-padhi@ti.com>
Tested-by: Judith Mendez <jm@ti.com>
Reviewed-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20250513054510.3439842-27-b-padhi@ti.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>