Staging: lustre: ldlm_pool: Drop wrapper function

Remove the function ldlm_pool_get_limit() and replace 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>