sdhci-pci: use X86_MDFLD to replace X86_MRST

sdhci-pci: use X86_MDFLD to replace X86_MRST

BZ: 22235

In R3, kernel is using X86_MDFLD but not X86_MRST for MFLD
project. sdhci-pci.c need to be updated accordingly otherwise
some functions depends on X86_MDFLD cannot be used.

Change-Id: Ica51ad2095d497cf7bee00e44f510cb3cc5678c0
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Reviewed-on: http://android.intel.com:8080/33851
Reviewed-by: Tang, Richard <richard.tang@intel.com>
Reviewed-by: Gross, Mark <mark.gross@intel.com>
Tested-by: Sun, Jianhua <jianhua.sun@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>