This implements the target NFC digital operations tg_configure_hw(),
tg_listen(), tg_listen_mdaa(), and tg_send_cmd().

The target mode supports NFC-A technology at 106kbits/s and NFC-F
technologies at 212 and 424kbits/s.
Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Cc: Stephen Tiedemann <stephen.tiedemann@gmail.com>
Tested-by: Cho, Yu-Chen <acho@suse.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>