arm: mx6: gw_ventana: Change clock init to enable NAND related clocks

arm: mx6: gw_ventana: Change clock init to enable NAND related clocks

Otherwise NAND booting is likely to fail. Since this disables the NAND related
clocks and SPL can't load the main U-Boot from NAND.

This problem was introduced with this patch:

e25fbe3f (gw_ventana: Move the DCD settings to spl code)

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>