spi: use generic gpio calls in spi_s3c24xx_gpio

Change the spi_s3c2410 driver to use the generic gpio calls that are now
available.

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>