Fix chunk ID validation

According to EA IFF 85:

Type IDs

A "type ID", "property name", "FORM type", or any other IFF identifier
is a 32-bit value: the concatenation of four ASCII characters in the
range R S (SP, hex 20) through R~S (hex 7E). Spaces (hex 20) should
not precede printing characters; trailing spaces are ok. Control characters
are forbidden.

taglib/dsdiff/dsdifffile.cpp

@@ -66,7 +66,7 @@ namespace
       return false;
 
     for(int i = 0; i < 4; i++) {
-      if(name[i] < 32 /*|| name[i] > 127*/)
+      if(name[i] < 32 || name[i] > 126)
         return false;
     }