BdsPlatform: generate SMM events to put eMMC/SD in proper mode

For Baytrail devices, coreboot leaves the eMMC/SD in PCI mode to enable
detection by Tianocore, so put into ACPI mode before OS boots.
Fixes booting on Baytrail devices.

Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>

CorebootModulePkg/Library/CorebootBdsLib/BdsPlatform.c

@@ -1265,6 +1265,11 @@ Returns:
   Status = gBS->SetTimer (UserInputDurationTime, TimerRelative, 20000000);
   ASSERT (Status == EFI_SUCCESS);
 
+  //
+  // invoke SMM handler to put eMMC/SD devices into ACPI mode for OS
+  //
+  IoWrite8(0xb2, 0xcd);
+
   //
   // To give the User a chance to enter Setup here, if user set TimeOut is 0.
   // BDS should still give user a chance to enter Setup