mmc: sdhci: Dont enable CDR for tuning commands

Currently we enable CDR for every read command including
for tuning procedure which is not correct (as CDR if
enabled might correct the phase during tuning and we
wont be able to detect the correct phase during tuning).

So, disable CDR for read tuning commands.

CRs-fixed: 759398
Change-Id: I051b6e3b204dde22cdc973759c3e32d0a81c369a
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>