[rdk-extender] down/up the primary bridge on wifi siwtch

Reason for change: brlan0 should be made down and up
when switching from ethernet to wifi to get IP.

Change-Id: I13b8f86bff5e0036d17624d96b2867623c0ab3fb
Signed-off-by: Akilesh K <quic_akilkart@quicinc.com>