The SPI controller configuration during the init can be reused, for the
resume function for example.

Let's move this configuration to a separate function.
Signed-off-by: NQuentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: NNicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: NMark Brown <broonie@kernel.org>