[ARM] S3C: Add UART FIFO selection during arch decompression

Add a configuration option to start the UART FIFOs during the
decompressions sequence to improve boot time when the bootloader
fails to enable the UART FIFOs.

For example, the SMDK6410 UBoot 1.1.6 leaves the FIFOs off.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>