ASoC: soc-cache: Add spi_write support for all I/O types

Ensure that all drivers that use SPI and I2C will work properly
by providing SPI write functions for all different I/O types.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>