mmc: sdhci-of-esdhc: Access Freescale eSDHC registers as 32-bit

Freescale eSDHC registers only support 32-bit accesses, this patch
ensures that all Freescale eSDHC register accesses are 32-bit.

Signed-off-by: Xu lei <B33228@freescale.com>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>