ice: Get rid of ice_cleanup_header

ice_cleanup_hdrs() has been stripped of most of its content, it only serves
as a wrapper for eth_skb_pad(). We can get rid of it altogether and
simplify the codebase.

Signed-off-by: Krzysztof Kazimierczak <krzysztof.kazimierczak@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>