virtio: remove admin-up flag during interface creation

virtio: remove admin-up flag during interface creation

Type: fix

During the interface creation time, (by default) admin-up
flag is locally set for tap and virtio interfaces.
While, in VPP the state of these interfaces are still
admin-down. User needs to explicitly call
'set interface state <interface-name> up' to admin-up the
newly created tap or virtio interface(s) in VPP. So, this
behavior is inconsistent.

This patch fixes the issue to have consistent behavior
for given interface between local and global administration
state.

Change-Id: Ifd8904a09fbdbe7b386874ac3231dc0527064518
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>