mmc: core: set enhanced strobe as true

Now that we are using mmc_select_hs400 instead of mmc_select_hs400es,
set ios.enhanced_strobe as true if enhanced strobe is working and
supported in card.

Change-Id: I1af3eaa083b737491a2bf3da4655511c7789f586
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>