ice: don't ignore return codes in VSI related code

There were few smatch warnings reported by Dan:
- ice_vsi_cfg_xdp_txqs can return 0 instead of ret, which is cleaner
- return values in ice_vsi_cfg_def were ignored
- in ice_vsi_rebuild return value was ignored in case rebuild failed,
  it was a never reached code, however, rewrite it for clarity.
- ice_vsi_cfg_tc can return 0 instead of ret

Fixes: 6624e780 ("ice: split ice_vsi_setup into smaller functions")
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>