spi: lpspi: enable runtime pm for lpspi

Enable the runtime power management for lpspi module.

Do some adaptation work from kernel 4.9 to 4.14.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Signed-off-by: Han Xu <han.xu@nxp.com>
Reviewed-by: Frank Li <frank.li@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>