mmc: omap_hsmmc: Enable Auto CMD12

Enable Auto-CMD12 for multi block read/write on HSMMC.
Tested on OMAP4430, OMAP3430 and OMAP2430 SDP

Signed-off-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>