spi: cadence-qspi: add system-wide suspend and resume callbacks

spi: cadence-qspi: add system-wide suspend and resume callbacks

Each SPI controller is expected to call the spi_controller_suspend() and
spi_controller_resume() callbacks at system-wide suspend and resume.

It (1) handles the kthread worker for queued controllers and (2) marks
the controller as suspended to have spi_sync() fail while the
controller is unavailable.

Those two operations do not require the controller to be active, we do
not need to increment the runtime PM usage counter.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://msgid.link/r/20240222-cdns-qspi-pm-fix-v4-4-6b6af8bcbf59@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>