spi: imx: fix runtime pm support for !CONFIG_PM

spi: imx: fix runtime pm support for !CONFIG_PM

525c9e5a32bd introduced pm_runtime support for the i.MX SPI driver. With
this pm_runtime is used to bring up the clocks initially. When CONFIG_PM
is disabled the clocks are no longer enabled and the driver doesn't work
anymore. Fix this by enabling the clocks in the probe function and
telling pm_runtime that the device is active using
pm_runtime_set_active().

Fixes: 525c9e5a32bd spi: imx: enable runtime pm support
Tested-by: Christian Eggers <ceggers@arri.de> [tested for !CONFIG_PM only]
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20201021104513.21560-1-s.hauer@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>