mmc: pxa: Flip over the remaining boards to pxa_mmc_generic

Some of the boards still used the old PXA_MMC driver instead of the
new generic one. Use the new one instead so the old can be removed
and the generic MMC framework can be properly used.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andy Fleming <afleming@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>