Generic/CallTimePassByReference: remove unreachable condition

Removes a condition that checks if `nested_parenthesis` property of
the variable or short syntax array is not set. As far as I can check,
this condition can never be true. A few lines above, we are already
checking for the presence of opening and closing parentheses and the
while loop is limited to T_VARIABLE and T_OPEN_SHORT_ARRAY inside the
parentheses. Since it is limited to tokens inside the parentheses,
`nested_parenthesis` will always be set.

The removed check was added in this commit that added defensive code to
protect against syntax errors to a few sniffs:
0e42098

Author: rodrigoprimo

src/Standards/Generic/Sniffs/Functions/CallTimePassByReferenceSniff.php

@@ -86,10 +86,6 @@ public function process(File $phpcsFile, $stackPtr)
         ];
 
         while (($nextSeparator = $phpcsFile->findNext($find, ($nextSeparator + 1), $closeBracket)) !== false) {
-            if (isset($tokens[$nextSeparator]['nested_parenthesis']) === false) {
-                continue;
-            }
-
             if ($tokens[$nextSeparator]['code'] === T_OPEN_SHORT_ARRAY) {
                 $nextSeparator = $tokens[$nextSeparator]['bracket_closer'];
                 continue;