spi_s3c24xx: fix section warning

Fix the section mismatch warning generated by the incorrect naming of
s3c24xx_spidrv which should be s3c24xx_spi_driver:

WARNING: drivers/spi/spi_s3c24xx.o(.data+0x4):
  Section mismatch in reference from the variable s3c24xx_spidrv
  to the (unknown reference) .exit.text:(unknown)

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>