spi_s3c24xx: pin configuration updates

Add a pin configuration callback for the s3c24xx SPI driver, as there are
several options depending on the channel and the chip in use.

This is needed as the controller may not have been setup by the initial
bootloader and the fact that the SPI controller gets reset over
suspend/resume into slave mode but the GPIO function registers do not.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>