ofproto: Break out resubmit resource checking

Break out resubmit resource checking into a helper function
xlate_resubmit_resource_check() and use this new function.
This is to allow the check to be re-used by a subsequent patch.

Suggested-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Ben Pfaff <blp@nicira.com>