rocker: rename rocker.c to rocker_main.c

Since "rocker.c" is going to be split into multiple files, start with
renaming original "rocker.c" file to "rocker_main.c". Multiple code
parts are going to be cut from "rocker_main.c" later on.

Fix couple of checkpatch issues on the way.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>