[ARM] 4328/1: Move i.MX UART regs to driver

This patch moves the i.MX UART register descriptions from
include/asm-arm/arch-imx/imx-regs.h to the serial driver itself.
This helps using the driver on other architectures like mx31

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>