ArmPkg/ArmMmuLib: Explicitly cast UINT32 data conversions

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2835

There's several occurrences of a UINT64 or an EFI_PHYSICAL_ADDRESS
being assigned to a UINT32 value in ArmMmuLib. These result in
warning C4244 in VS2019:

warning C4244: '=': conversion from 'UINT64' to 'UINT32', possible
loss of data

warning C4244: '=': conversion from 'EFI_PHYSICAL_ADDRESS' to
'UINT32', possible loss of data

This change explicitly casts the values to UINT32.

These can be reproduced with the following build command:
build -b DEBUG -a ARM -t VS2019 -p ArmPkg/ArmPkg.dsc
-m ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c

@@ -225,7 +225,7 @@ FillTranslationTable (
     return;
   }
 
-  PhysicalBase = MemoryRegion->PhysicalBase;
+  PhysicalBase = (UINT32)MemoryRegion->PhysicalBase;
   RemainLength = MIN(MemoryRegion->Length, SIZE_4GB - PhysicalBase);
 
   switch (MemoryRegion->Attributes) {
@@ -291,7 +291,7 @@ FillTranslationTable (
       PhysicalBase += TT_DESCRIPTOR_SECTION_SIZE;
       RemainLength -= TT_DESCRIPTOR_SECTION_SIZE;
     } else {
-      PageMapLength = MIN (RemainLength, TT_DESCRIPTOR_SECTION_SIZE -
+      PageMapLength = MIN ((UINT32)RemainLength, TT_DESCRIPTOR_SECTION_SIZE -
                                          (PhysicalBase % TT_DESCRIPTOR_SECTION_SIZE));
 
       // Case: Physical address aligned on the Section Size (1MB) && the length