NFC: trf7970a: Add driver with ISO/IEC 14443 Type 2 Tag Support

Add a driver for the Texas Instruments TRF7970a RFID/NFC/15693
transceiver.  The driver currently supports ISO/IEC 14443 Type 2
tags only (MIFARE Ultralight and Ultralight C but not Classic).

CC: Erick Macias <emacias@ti.com>
CC: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/nfc/Makefile b/drivers/nfc/Makefile
index 56ab822..ae42a3f 100644
--- a/drivers/nfc/Makefile
+++ b/drivers/nfc/Makefile
@@ -10,5 +10,6 @@
 obj-$(CONFIG_NFC_SIM)		+= nfcsim.o
 obj-$(CONFIG_NFC_PORT100)	+= port100.o
 obj-$(CONFIG_NFC_MRVL)		+= nfcmrvl/
+obj-$(CONFIG_NFC_TRF7970A)	+= trf7970a.o
 
 ccflags-$(CONFIG_NFC_DEBUG) := -DDEBUG