aarch64: Fix coding style issue in `aarch64-dis.c'

Fix integer value being returned from boolean function, as introduced
in `aarch64: Remove asserts from operand qualifier decoders [PR31595]'.

opcodes/aarch64-dis.c

@@ -1038,7 +1038,7 @@ aarch64_ext_ft (const aarch64_operand *self ATTRIBUTE_UNUSED,
 	return false;
       info->qualifier = get_sreg_qualifier_from_value (value);
       if (info->qualifier == AARCH64_OPND_QLF_ERR)
-	return 0;
+	return false;
     }
 
   return true;