mmc: tegra: Add tuning support for 81.6 MHz.

mmc: tegra: Add tuning support for 81.6 MHz.

-Add tuning support for 81.6 MHz.
-For T124 SDMMC, 81.6 tuning should be done at both
boot and min vcore override voltages.
-For T124 high frequency tap procedure should be used
for 81.6 MHz.

Bug 1339288
Bug 1323956

Change-Id: I0608ff1ebaf88b38e9e4e6a1a2df0d878aab83f7
Signed-off-by: Naveen Kumar Arepalli <naveenk@nvidia.com>
Signed-off-by: R Raj Kumar <rrajk@nvidia.com>
Reviewed-on: http://git-master/r/300544
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Venu Byravarasu <vbyravarasu@nvidia.com>