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/SdMmcPciHci.c

@@ -931,6 +931,8 @@ SdMmcHcClockSupply (
     }
   }
 
+  Private->Slot[Slot].CurrentFreq = ClockFreq;
+
   return Status;
 }