NFC: st95hf: drop illegal kfree_skb()

The skb that is passed in to ->in_send_cmd() is freed by the core when the
function returns. Calling kfree_skb() on it from the driver callback will
hence lead to a double-free.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>