ice: Remove possible null dereference

Commit 1f45ebe0 ("ice: add extra check for null Rx descriptor") moved
the call to ice_construct_skb() under a null check as Coverity reported a
possible use of null skb. However, the original call was not deleted, do so
now.

Fixes: 1f45ebe0

 ("ice: add extra check for null Rx descriptor")
Reported-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>