rocker: introduce be put/get variants and use it when appropriate

This kills the sparse warnings.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
---
v1->v2:
-no change
rocker: fix eth_type type in struct rocker_ctrl

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
---
v1->v2:
-fixed typo in subject pointed out by Sergei