NFC: digital: Set the command pending flag

There is a flag in the command structure indicating that this command is
pending. It was checked before sending the command to not send the same
command twice but it was actually never set. This is now fixed.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>