datapath: Increase maximum number of actions per flow.

datapath: Increase maximum number of actions per flow.

Until now the number of actions in a flow has been limited to what fits in
a page.  Each action is 8 bytes, and on 32-bit architectures there is a
12-byte header, so with 4-kB pages that limits flows to 510 actions.  We
and Citrix have noticed that OVS stops working properly after about 509
VIFs are added to a bridge.  According to log messages this is the reason:
at this point it is no longer possible to flood a packet to all ports.

This commit should help, by increasing the maximum number of actions in a
flow.  In the long term, though, we should adopt use of port groups or
otherwise reduce the number of actions needed to flood a packet.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Bug #3573.
NIC-234.