mmc: fsl_esdhc: Add support for DDR mode

Add support of the DDR mode for eSDHC driver.
Enable it for i.MX6 SoC family only.

Signed-off-by: Volodymyr Riazantsev <volodymyr.riazantsev@globallogic.com>
Reviewed-by: York Sun <yorksun@freescale.com>
3 files changed