ofproto: Fix compiler warnings.

ofproto: Fix compiler warnings.

This patch fixes the following warnings on my system:

lib/ofp-actions.c:458:13: error: format '%x' expects argument of
type 'unsigned int', but argument 4 has type 'long unsigned int'
[-Werror=format]

ofproto/ofproto.c:3940:13: error: comparison between 'enum
ofoperation_type' and 'enum nx_flow_update_event'
[-Werror=enum-compare]

ofproto/ofproto.c:3941:13: error: comparison between 'enum
ofoperation_type' and 'enum nx_flow_update_event'
[-Werror=enum-compare]

ofproto/ofproto.c:3942:13: error: comparison between 'enum
ofoperation_type' and 'enum nx_flow_update_event'
[-Werror=enum-compare]

Signed-off-by: Ethan Jackson <ethan@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>