spi: bcm2835: Implement shutdown callback

Make sure we clear the FIFOs, stop the block, disable the clock and
release the DMA channel.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20200528190605.24850-1-f.fainelli@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed