mmc: sdhci: Enable clock scaling feature

Add support for enabling clock scaling feature and indicate
the same to MMC core layer by setting the capability
MMC_CAP2_CLK_SCALE.

Change-Id: I24f144d3f727160c302966888fb439b3a39a0dde
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
[venkatg@codeaurora.org: sdhci_set_clock is now a library function
thats called from platform clock handler, make changes to address that]
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
[subhashj@codeaurora.org: fixed compilation error]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[xiaonian@codeaurora.org: fix trivial merge conflict]
Signed-off-by: Xiaonian Wang <xiaonian@codeaurora.org>
4 files changed