uboot-imx

mxs: Fix the memory init for MX23

The memory init is slightly different on MX23, thus split the memory
init for mx23 and mx28 into different functions.

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>