MdeModulePkg/SdMmcPciHcDxe: Send SEND_STATUS at lower frequency

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1140

To avoid stability issues on some designs the driver
will now send SEND_STATUS at previous, lower, frequency
when upgrading the bus timing.

Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Marcin Wojtas <mw@semihalf.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>

Signed-off-by: Mateusz Albecki <mateusz.albecki@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>

MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHcDxe.h

@@ -83,6 +83,7 @@ typedef struct {
   BOOLEAN                            MediaPresent;
   BOOLEAN                            Initialized;
   SD_MMC_CARD_TYPE                   CardType;
+  UINT64                             CurrentFreq;
   EDKII_SD_MMC_OPERATING_PARAMETERS  OperatingParameters;
 } SD_MMC_HC_SLOT;