ARM: S3C24XX: Fix UART3 submask on S3C2416 and S3C2443

The UART3 submask should be 0x7 (SUBSRCPND[26:24]).

Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Sangbeom Kim <sbkim73@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>