Fix reset the vlan flags when main interface is deleted.
Fix reset the vlan flags when main interface is deleted.

The dot1q_vlans & dot1ad_vlans should be reset to 0 when main interface
is deleted. Otherwise, VPP will crash if the same interface index is reused
without attaching the sub interface on it.

Change-Id: I484d4a8892ff4241a3a32b22189746193d5f2594
Signed-off-by: Steve Shin <491df9b5284ac2b453f2c8add402bc5aa7e615e9@cisco.com>

FDio/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp