Patch from Deepak Saxena

This allows the serial driver autconf to work properly on all the IXP
serial ports. W/o it we basically put the serial port in an unrecoverable
state and lose console.
Signed-off-by: NDeepak Saxena <dsaxena@plexity.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>