If pppoe is used for wan access. script set 'eth1' as interface for curl
call. The correct interface is however 'pppoe-wan'.
These scripts use 'network_get_physdev' function to get real device for
bind_network but this is wrong. We need instead the l3_device of the the
logical interface.
In case if we don't use pppoe connection - 'l3_device' is equal to real device.
Follow P/R:
#14431
Signed-off-by: Coia Prant <coiaprant@gmail.com>