spi: s3c64xx: Added support for exynos5440 spi

This patch adds support for the exynos5440 spi controller.
The integration of the spi IP in exynos5440 is different from
other SoC's. The I/O pins are no more configured via gpio, they
have dedicated pins.

Signed-off-by: Girish K S <ks.giri@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>