dfu: tftp: update: Provide tftp support for the DFU subsystem

This commit adds initial support for using tftp for downloading and
upgrading firmware on the device.

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/dfu/Makefile b/drivers/dfu/Makefile
index cebea30..61f2b71 100644
--- a/drivers/dfu/Makefile
+++ b/drivers/dfu/Makefile
@@ -10,3 +10,4 @@
 obj-$(CONFIG_DFU_NAND) += dfu_nand.o
 obj-$(CONFIG_DFU_RAM) += dfu_ram.o
 obj-$(CONFIG_DFU_SF) += dfu_sf.o
+obj-$(CONFIG_DFU_TFTP) += dfu_tftp.o