mmc: sdhci: enable preset value after uhs initialization

mmc: sdhci: enable preset value after uhs initialization

According to the Host Controller spec v3.00, setting Preset Value Enable
in the Host Control2 register lets SDCLK Frequency Select, Clock Generator
Select and Driver Strength Select to be set automatically by the Host
Controller based on the UHS-I mode set. This patch enables this feature.
Since Preset Value Enable makes sense only for UHS-I cards, we enable this
feature after successfull UHS-I initialization. We also reset Preset Value
Enable next time before initialization.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.

Signed-off-by: Arindam Nath <[email protected]>
Reviewed-by: Philip Rakity <[email protected]>
Tested-by: Philip Rakity <[email protected]>
Acked-by: Zhangfei Gao <[email protected]>
Signed-off-by: Chris Ball <[email protected]>