MMC: omap_hsmmc: enable interface clock before calling mmc_host_enable()

The code path entered via mmc_host_enable() can include register
accesses to the HSMMC IP block.  For this to work, both the device
interface clock and functional clock need to be enabled before
mmc_host_enable() is called.  However, omap_hsmmc_probe() calls
mmc_host_enable() before enabling the device interface clock.

Fix by calling mmc_host_enable() after the device interface clock is
enabled.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Madhusudhan Chikkature Rajashekar <madhu.cr@ti.com>
Cc: Adrian Hunter <adrian.hunter@nokia.com>
Cc: Kishore Kadiyala <kishore.kadiyala@ti.com>
Cc: Tero Kristo <Tero.Kristo@nokia.com>
Acked-by: Madhusudhan Chikkature Rajashekar <madhu.cr@ti.com>