mmc: esdhc: add PIO mode support

For some FSL ESDHC controllers (e.g. P2020E, Rev1.0), the SDHC can not
work on DMA mode because of the hardware bug, so we set a broken dma flag
and use PIO mode.

Signed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Gao Guanhua <B22826@freescale.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>