spi: davinci: invoke chipselect callback

Davinci needs to configure chipselect on transfer.

Fixes: 4a07b8bc ("spi: bitbang: Make chipselect callback optional")
Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Link: https://lore.kernel.org/r/735fb7b0-82aa-5b9b-85e4-53f0c348cc0e@nokia.com


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