Merge tag 'spi-dw-set-cs' of...

Merge tag 'spi-dw-set-cs' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi into spi-4.19

spi: dw: Allow custom set_cs_callback

Allow platform specific drivers to provide their own set_cs callback when
the IP integration requires it.