ArmPkg: Fix Ecc error 5007 in CompilerIntrinsicsLib

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/CompilerIntrinsicsLib/memcmp_ms.c

@@ -18,8 +18,11 @@ int memcmp(void *, void *, size_t);
 #pragma function(memcmp)
 int memcmp(const void *s1, const void *s2, size_t n)
 {
-  unsigned char const *t1 = s1;
-  unsigned char const *t2 = s2;
+  unsigned char const *t1;
+  unsigned char const *t2;
+
+  t1 = s1;
+  t2 = s2;
 
   while (n-- != 0) {
     if (*t1 != *t2)