nand_spl: change out_be32 to raw_writel and depend on subsequent sync

This change reduces the SPL size by removing the redundant syncs produced
by out_be32 and just replies on one final sync

Done with:

sed -r '/in_be32/b; s/(out_be32)\(([^,]*),\s+(.*)\)/__raw_writel(\3, \2)/g' -i `git grep --name-only sdram_init nand_spl/`

Signed-off-by: Matthew McClintock <msm@freescale.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>