spi: rspi: Fix invalid SPI use during system suspend

If the SPI queue is running during system suspend, the system may lock
up.

Fix this by stopping/restarting the queue during system suspend/resume,
by calling spi_master_suspend()/spi_master_resume() from the PM
callbacks.  In-kernel users will receive an -ESHUTDOWN error while
system suspend/resume is in progress.

Based on a patch for sh-msiof by Gaku Inami.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org