ixgbe: Remove conversion to bool in ixgbe_device_supports_autoneg_fc()

No need to convert '==' expression to bool. This fixes the following
coccicheck warning:

drivers/net/ethernet/intel/ixgbe/ixgbe_common.c:68:11-16: WARNING:
conversion to bool not needed here

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>