Fix For Wildcard-containing only_db failure in sidebar

This commit fixes the Bug #4242. The "only_db"directive  now accepts
MySQL LIKE wildcards without errors.Changes have been made to the
function getData() in phpmyadmin/libraries/navigation/Nodes/Node.class.php .
The if-else clause has been removed. The checking of the "only_db"
directive is now performed solely by the function
getWhereClause()in the same class.

Signed-off-by: Vasu Bhardwaj <voodoorapter014@gmail.com>