mmc: core: Fix the issue with clock scaling in resume-scaling

In resume_scaling, the host current clock is compared with max clock
of the card to adjust the current-scaling clock.

If max clock supported by the card is more than the max clock that the
host can support, then the above-mentioned comparison is resulting in
setting the current-scaling clock to scale-down clock frequency even
though current host clock is at the maximum clock. This will lead to
skipping of scaling down to lower clock in low load use-cases. So clock
would remain at max clock till next time clock is scaled up and then
scaled down.

To prevent this scenario, compare the host current clock with max clock
that host can be scaled-up instead of max clock of the card.

Change-Id: Ibbed4bb374f1cbb5aee21cfca4e7e97d8f999d51
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>