kernel-doc/rst: drop redundant unescape in highlighting

This bit is already done by xml_unescape() above.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index e0fd14f..8f9eac5 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -1796,7 +1796,6 @@
 	if ($line eq "") {
 	    print $lineprefix, $blankline;
 	} else {
-	    $line =~ s/\\\\\\/\&/g;
 	    print $lineprefix, $line;
 	}
 	print "\n";