ice: Fix a few null pointer dereference issues

1) When ice_ena_msix_range() fails to reserve vectors, a devm_kfree()
   warning was seen in the error flow path. So check pf->irq_tracker
   before use in ice_clear_interrupt_scheme().

2) In ice_vsi_cfg(), check vsi->netdev before use.

3) In ice_get_link_status, check link_up before use.

Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>