spi/sh-msiof: Remove unneeded empty runtime PM callbacks
spi/sh-msiof: Remove unneeded empty runtime PM callbacks

Previously the runtime PM API insisted on having callbacks for everything
but this requirement was removed a while ago so the empty callbacks can
also be removed.

Signed-off-by: Mark Brown <b51b9a92386687a9ac927cebfa0f978adeb8cea5@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs