igb: use BIT() macro or unsigned prefix

igb: use BIT() macro or unsigned prefix

For bitshifts, we should make use of the BIT macro when possible, and
ensure that other bitshifts are marked as unsigned. This helps prevent
signed bitshift errors, and ensures similar style.

Make use of GENMASK and the unsigned postfix where BIT() isn't
appropriate.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit a51d8c217b15b97fede844dd6860f7b3c6ffcfef)

Orabug: 26325580

Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>