StandaloneMmPkg/Core: Fix the failure to find uncompressed inner FV

The MmCoreFfsFindMmDriver only checks for encapsulated compressed FVs.
When an inner FV is uncompressed, StandaloneMmCore will miss the FV and
all the MM drivers in the FV will not be dispatched.
Add checks for uncompressed inner FV to fix this issue.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Wei6 Xu <wei6.xu@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

StandaloneMmPkg/Core/FwVol.c

@@ -79,6 +79,8 @@ MmCoreFfsFindMmDriver (
   UINTN                       DepexSize;
   UINTN                       Index;
   EFI_COMMON_SECTION_HEADER   *Section;
+  VOID                        *SectionData;
+  UINTN                       SectionDataSize;
   UINT32                      DstBufferSize;
   VOID                        *ScratchBuffer;
   UINT32                      ScratchBufferSize;
@@ -115,6 +117,26 @@ MmCoreFfsFindMmDriver (
       break;
     }
 
+    //
+    // Check uncompressed firmware volumes
+    //
+    Status = FfsFindSectionData (
+               EFI_SECTION_FIRMWARE_VOLUME_IMAGE,
+               FileHeader,
+               &SectionData,
+               &SectionDataSize
+               );
+    if (!EFI_ERROR (Status)) {
+      if (SectionDataSize > sizeof (EFI_FIRMWARE_VOLUME_HEADER)) {
+        InnerFvHeader = (EFI_FIRMWARE_VOLUME_HEADER *)SectionData;
+        MmCoreFfsFindMmDriver (InnerFvHeader, Depth + 1);
+        continue;
+      }
+    }
+
+    //
+    // Check compressed firmware volumes
+    //
     Status = FfsFindSection (
                EFI_SECTION_GUID_DEFINED,
                FileHeader,