SystemUI: Add ethernet network icon

Add an ethernet network icon to the statusbar network area.

Change-Id: I019740f360b5f9cc85f404f75d38e38896182a81
SystemUI: Fix missing context var

Change-Id: I083f85fdfec2bde88e6d8e0366d94e86eaea20cd
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>