The implementation of mmc_select_hwpart() was cribbed from do_mmcops().
Update do_mmcops() to call mmc_select_hwpart() to avoid duplication.

<panto> Manual patch update due to patch order.

Acked-by: Pantelis Antoniou <panto@antoniou-consulting.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>