[ARM] 3258/1: IMX serial: fix parity

Patch from Matt Reimer

IMX serial parity generation doesn't work because of a simple logic error. This patch fixes it and now Bluetooth works on R1000.

Signed-off-by: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>