rocker: rename rocker.h to rocker_hw.h

Since "rocker.h" file is going to be used for different purpose,
rename the hardware-specific header to "rocker_hw.h".

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