Tokenizer/PHP: minor tweak

Prevents some unnecessary token changes of the type `token 4 changed from T_STRING to T_STRING`.

Author: jrfnl

src/Tokenizers/PHP.php

@@ -1469,6 +1469,7 @@ protected function tokenize($string)
 
                     if ($x < $numTokens
                         && is_array($tokens[$x]) === true
+                        && $tokens[$x][0] !== T_STRING
                         && $tokens[$x][0] !== T_NAME_QUALIFIED
                     ) {
                         if (PHP_CODESNIFFER_VERBOSITY > 1) {