mmc: sdhci: Add HS400 Enhanced Strobe support

Delegate setting the Enhanced Strobe configuration to individual drivers
if they set a function for it. Return -ENOTSUPP if they do not, like
what the MMC uclass does.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>