mmc: omap_hsmmc: Remove unnecessary callbacks from platform data

These callbacks are set during driver probe and not from the platform
init, -- evtl. they had been for oamp 1/2 -- for omap3 they are local
functions of the driver. These indirection could be dropped
altogether in favor of regular function calls TODO

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>