mmc: omap_hsmmc: Add tuning support

HS200/SDR104 requires tuning command to be sent to the card. Use
the mmc_send_tuning library function to send the tuning
command and configure the internal DLL.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>