ARM: SAMSUNG: Add naming of s3c64xx-spi devices

Commit a5238e36 (spi: s3c64xx: move controller information into driver
data) introduced separate device names for the different subtypes of the
spi controller but forgot to set these in the relevant machines.

To fix this introduce a s3c64xx_spi_setname function and populate all
Samsung arches with the correct names. The function resides in a new
header, as the s3c64xx-spi.h contains driver platform data and should
therefore at some later point move out of the Samsung include dir.

Tested on a s3c2416-based machine.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Cc: Stable <stable@vger.kernel.org>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
[s.nawrocki@samsung.com: tested on mach-exynos]
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>