ofp-actions: Include OFPACT_REG_MOVE in action set

Treating OFPACT_REG_MOVE as a "set" action preserves the order of loads
and moves and allows a load to overwrite a previous move to the same
register.

This makes the following work:

add-group br0 group_id=1234,type=all, \
              bucket=output:10,move:NXM_NX_REG1[]->NXM_OF_IP_SRC[], \
			  bucket=output:11
add-flow br0 ip actions=load:0xffffffff->NXM_NX_REG1[],group:1234

Signed-off-by: Thomas Graf <tgraf@noironetworks.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>