ARM: SAMSUNG: Fix typo "CONFIG_SAMSUNG_DEV_RTC"

s3c_rtc_setname() tests for CONFIG_SAMSUNG_DEV_RTC or
CONFIG_PLAT_S3C24XX. But of these two macros only CONFIG_PLAT_S3C24XX
actually exists. Now we can see that s3c_device_rtc is only defined if
either CONFIG_PLAT_S3C24XX or CONFIG_S3C_DEV_RTC are defined. So,
apparently, it was intended to use CONFIG_S3C_DEV_RTC here.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>