iavf: make functions static where possible

[ Upstream commit a4aadf0f

 ]

Make all possible functions static.

Move iavf_force_wb() up to avoid forward declaration.

Suggested-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Stable-dep-of: c2ed2403

 ("iavf: Wait for reset in callbacks which trigger it")
Signed-off-by: Sasha Levin <sashal@kernel.org>