rocker: introduce rocker_tlv_for_each_nested helper and use it

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
rocker: add missed UNSPEC values

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
rocker: prefix rx/tx related hw defines with "ROCKER_" to make the namespace clear

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>