ovs-bugtool: Don't run a few ethtool commands on virtual devices.

ovs-bugtool: Don't run a few ethtool commands on virtual devices.

There can be a few hundred virtual interfaces in a hypervisor.
Some of the ethtool commands that we currently run on these devices
probably does not provide any extra information. So remove them
for tap and vif interfaces.

Also bump up the size limitation for CAP_NETWORK_STATUS. The
current value is quite low and a 50 MB limit pre-compression
does not add much to the overall size.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>