NFC: st-nci: fix use of uninitialized variables in error path

st_nci_hci_load_session() calls kfree_skb() on unitialized
variables skb_pipe_info and skb_pipe_list if the call to
nci_hci_connect_gate() failed. Reword the error path to not use
these variables when they are not initialized. While at it, there
seemed to be a memory leak because skb_pipe_info was only freed
once, after the for-loop, even though several ones were created
by nci_hci_send_cmd.

Cc: stable@vger.kernel.org
Acked-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>