bnxt_en: Use auxiliary bus calls over proprietary calls

Wherever possible use the function ops provided by auxiliary bus
instead of using proprietary ops.

Defined bnxt_re_suspend and bnxt_re_resume calls which can be
invoked by the bnxt_en driver instead of the ULP stop/start calls.

Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>