spi: omap2-mcspi: Activate pinctrl idle state during runtime suspend

Set the (optional) idle pinctrl state during runtime suspend. This is the
same schema used in PL022 driver and can help with HW designs sharing
the SPI lines for different purposes.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20210222023243.491432-1-alexander.sverdlin@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>