remoteproc: Use of_reserved_mem_region_* functions for "memory-region"

remoteproc: Use of_reserved_mem_region_* functions for "memory-region"

Use the newly added of_reserved_mem_region_to_resource() and
of_reserved_mem_region_count() functions to handle "memory-region"
properties.

The error handling is a bit different in some cases. Often
"memory-region" is optional, so failed lookup is not an error. But then
an error in of_reserved_mem_lookup() is treated as an error. However,
that distinction is not really important. Either the region is available
and usable or it is not. So now, it is just
of_reserved_mem_region_to_resource() which is checked for an error.

Acked-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Tested-by: Peng Fan <peng.fan@nxp.com> # i.MX93-11x11-EVK for imx_rproc.c
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> # rcar
Tested-by: Beleswar Padhi <b-padhi@ti.com> # TI
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20251124182751.507624-1-robh@kernel.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>