spi: S3C2410: add bus number to SPI GPIO driver

Allow passing a bus number through the platform data for the S3C2410 SPI
GPIO driver.   This is needed to support multiple SPI busses.

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>