spi: spi-rockchip: cleanup use struct spi_controller

Cleanup, move from the compatibily layer struct spi_master over
to struct spi_controller, and rename the related function calls.
Signed-off-by: Chris Ruehl <chris.ruehl@gtsys.com.hk>
Link: https://lore.kernel.org/r/20200511083022.23678-2-chris.ruehl@gtsys.com.hkSigned-off-by: Mark Brown <broonie@kernel.org>