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>