spi: Add spi driver for Socionext SynQuacer platform

This patch adds support for controller found on synquacer platforms.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>