netdev-linux: Fix ingress policing burst rate configuration via tc

netdev-linux: Fix ingress policing burst rate configuration via tc

The tc_police structure was filled with a value calculated in bits
instead of bytes while bytes were expected. This led the setting
of an x8 higher burst value.

Documentation and defaults have been corrected accordingly to minimize
nuisances on users sticking to the defaults.

The suggested burst value is now 80% of policing rate to make sure
TCP works correctly.

Signed-off-by: Miguel Angel Ajo <majopela@redhat.com>
Tested-by: Miguel Angel Ajo <majopela@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>