spi: dt-bindings: mpfs-spi: permit resets

spi: dt-bindings: mpfs-spi: permit resets

CoreSPI, CoreQSPI and the hardened versions of them on mpfs and
pic64gx have a reset pin. For the first two, usually this is wired to
a common fabric reset not managed by software and for the latter two
the platform firmware takes them out of reset on first-party boards
(or those using modified versions of the vendor firmware), but not all
boards may take this approach. Permit providing a reset in devicetree
for Linux, or other devicetree-consuming software, to use.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20260303-deceiver-rack-82f2b89eac40@spud
Signed-off-by: Mark Brown <broonie@kernel.org>