datapath: Convert ODP_FLOW_* and ODP_EXECUTE to put dp_idx into message.

datapath: Convert ODP_FLOW_* and ODP_EXECUTE to put dp_idx into message.

When the datapath moves to the Netlink protocol it won't have a minor
number to use, so we have to put the dp_idx in the message.

This also changes the kernel implementation of ODP_FLOW_FLUSH to do the
datapath locking inside flush_flows() instead of inside openvswitch_ioctl()
but doesn't change that command's userspace interface, which still passes
a datapath number as the ioctl argument.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>