mmc: host: sdhci-msm-ice: Fix clang warning with NOT operator usage

Make the logical expression more explicit for removing dubiousness.

With the present expression, clang warnings are reported. Adding
parentheses also generates internal compilation warnings. So used an
extra variable for removing ambiguity.

Change-Id: Icd55088ca3985091efb4e27ff94f2cfb006a1855
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>