S3c24xx SPI controllers both select 'bitbang'

Tweak Kconfig for the S3C24XX SPI controller drivers. Both use the bitbang
framework; only one previously said that. Plus in this case "select" is
the right way to manage that dependency, since folk will not know up front
to enable bitbang in order to even see those S3C drivers in order to enable
them.

Signed-off-by: David Brownell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/spi/Kconfig

···
 config SPI_S3C24XX
 	tristate "Samsung S3C24XX series SPI"
 	depends on SPI_MASTER && ARCH_S3C2410 && EXPERIMENTAL
+	select SPI_BITBANG
 	help
 	  SPI driver for Samsung S3C24XX series ARM SoCs
 
 config SPI_S3C24XX_GPIO
 	tristate "Samsung S3C24XX series SPI by GPIO"
-	depends on SPI_MASTER && ARCH_S3C2410 && SPI_BITBANG && EXPERIMENTAL
+	depends on SPI_MASTER && ARCH_S3C2410 && EXPERIMENTAL
+	select SPI_BITBANG
 	help
 	  SPI driver for Samsung S3C24XX series ARM SoCs using
 	  GPIO lines to provide the SPI bus. This can be used where