mmc: sh_mmcif: enable MMC_MODE_HC

The controller can control high capacity cards. So, the patch adds
the flag. If the flag is not set, "mmcinfo" will fail when a high
capacity card is used.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>