ARM: SAMSUNG: Allow overriding of adc device name for S3C24XX

The adc blocks of S3C2443 and S3C2416 contain quirks not present
in the stock S3C24xx adc. Therefore allow them to alter the
device name via s3c_adc_setname.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>