meta-ampere: Support virtual Ethernet over USB device

Implement systemd service to create an Ethernet over USB interface
for communication between CPU and BMC.

Tested:
1. Check usb0 ethernet interface in BMC console
root@mtjade:~# ifconfig usb0
usb0      Link encap:Ethernet  HWaddr DA:F7:E9:A3:5A:0C
          inet addr:192.168.0.10  Bcast:192.168.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:412 (412.0 B)
2. Check USB Ethernet device on Host Linux
$ lsusb | grep Ethernet
Bus 001 Device 004: ID 1d6b:0103 Linux Foundation NCM (Ethernet) Gadget

Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
Signed-off-by: Thang Q. Nguyen <thang@os.amperecomputing.com>
Change-Id: Icb7c096df426233e8f2ee7318f2a1805f07ab3a7
diff --git a/meta-jade/conf/machine/mtjade.conf b/meta-jade/conf/machine/mtjade.conf
index c7bf92b..5999392 100644
--- a/meta-jade/conf/machine/mtjade.conf
+++ b/meta-jade/conf/machine/mtjade.conf
@@ -7,3 +7,7 @@
 require conf/distro/include/phosphor-isolation.inc
 
 VOLATILE_LOG_DIR = "no"
+
+OBMC_IMAGE_EXTRA_INSTALL_append = "\
+                                   ampere-usbnet \
+                                  "