ENGR00180882- MX6DL Add bus frequency scaling support.

ENGR00180882- MX6DL Add bus frequency scaling support.

Added support for changing DDR frequency on MX6DL.
During system IDLE, DDR freq can drop down to 24MHz
if none of the devices that need high AHB frequency
are active.
Changed the DDR code to handle both MX6Q and MX6DL
DDR and IOMUX settings.
Fixed bug associated incorrect IRAM memory allocation
used to store DDR and IOMUX data.

Signed-off-by: Ranjani Vaidyanathan <ra5478@freescale.com>