Staging: lustre: dir: Remove wrapper function

Remove the function ll_check_page() and replace all its calls with the
function it wrapped.

Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>