ads2armasm_ms: Match the indentation of the previous line

Instead of hardcoding a certain indentation, use the regexp to
provide similar indentation for the new line as well.

Change-Id: Iacb2621b35ce7e1aa3980c1603b8e3ab02d98a35

build/make/ads2armasm_ms.pl

@@ -32,7 +32,7 @@ while (<STDIN>)
 
     s/ldrneb/ldrbne/i;
     s/ldrneh/ldrhne/i;
-    s/(ENDP.*)/$&\n    ALIGN 4/;
+    s/^(\s*)ENDP.*/$&\n$1ALIGN 4/;
 
     print;
 }