ArmPkg: Fix Ecc error 5007 in ArmMmuLib

This patch fixes the following Ecc reported error:
There should be no initialization of a variable as
part of its declaration

Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c

@@ -220,7 +220,7 @@ UpdateSectionEntries (
   IN UINT64                    Attributes
   )
 {
-  EFI_STATUS    Status = EFI_SUCCESS;
+  EFI_STATUS    Status;
   UINT32        EntryMask;
   UINT32        EntryValue;
   UINT32        FirstLevelIdx;
@@ -231,6 +231,8 @@ UpdateSectionEntries (
   VOID          *Mva;
   volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
 
+  Status = EFI_SUCCESS;
+
   // EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)
   // EntryValue: values at bit positions specified by EntryMask