mmc: sdhci-msm: Correct the CDR toggle logic

We should keep either one of CDR_EN or CDR_EXT_EN enabled.
So correct this logic in toggle CDR function.

CRs-fixed: 759398
Change-Id: Ic137ae2a28e912ab131644ff9d81e41f4256dd05
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
Signed-off-by: Pavan Anamula <pavana@codeaurora.org>