NFC: digital: Fix potential skb leaks in NFC-DEP code

When digital_in_send_cmd() or digital_tg_send_cmd()
fail, they do not free the skb that was passed to
them so the routine that allocated the skb should
free it.  Currently, there are several routines in
the NFC-DEP code that don't do this so make them.

Reviewed-by: Thierry Escande <thierry.escande@linux.intel.com>
Tested-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>