MAINTAINERS: adjust file entry for ARM/APPLE MACHINE SUPPORT

MAINTAINERS: adjust file entry for ARM/APPLE MACHINE SUPPORT

Commit de614ac31955 ("MAINTAINERS: Add entries for Apple PWM driver") adds
an entry for Documentation/devicetree/bindings/pwm/pwm-apple.yaml, but
commit 87a3a3929c71 ("dt-bindings: pwm: Add Apple PWM controller") from
the same patch series actually adds the devicetree binding file with the
name apple,s5l-fpwm.yaml.

Adjust the file entry to the file actually added.

Fixes: de614ac31955 ("MAINTAINERS: Add entries for Apple PWM driver")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20230424114043.22475-1-lukas.bulwahn@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>