[ARM] 4722/1: S3C24XX: Improve output if watchdog reset fails

If the watchdog reset fails and we decided to take the jump
to zero approach, allow 50ms for the UARTS to drain the FIFOs
before calling into a bootloader that may flush the output.

Also reduece the waits and the timeout values as 5 seconds is
rather long.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>