link af ops: Add new ao_compare op to compare link af_data

This patch adds new operation to compare link af_data.
ao_compare is similar to object oo_compare operation.
This op can be used when two links are compared
 for their af data. It takes two link objects in
question, an object specific bitmask defining which
attributes should be compared and flags to control
the behaviour. The function must return a bitmask
with the relevant bit set for each attribute that mismatches.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Add ao_compare support to bridge family af_data

This patch adds support for ao_compare operation
to bridge link af data operations.

Adds field ce_mask to struct bridge_data to work
with the ATTR attributes. I can submit separate
patches to introduce mask field to ATTR macros.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Wilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>