dt-bindings: firmware: update arm,scpi.yaml reference

Changeset 1496be71 ("dt-bindings: firmware: arm,scpi: Convert to json schema")
renamed: Documentation/devicetree/bindings/arm/arm,scpi.txt
to: Documentation/devicetree/bindings/firmware/arm,scpi.yaml.

Update its cross-reference accordingly.

Fixes: 1496be71 ("dt-bindings: firmware: arm,scpi: Convert to json schema")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/b5a2b0cb83e7f8193b4be4cef9250dd4c42877ab.1626947923.git.mchehab+huawei@kernel.org


Signed-off-by: Guenter Roeck <linux@roeck-us.net>