ice: Fix a NULL vs IS_ERR() check in probe()

The ice_allocate_sf() function returns error pointers on error.  It
doesn't return NULL.  Update the check to match.

Fixes: 177ef7f1 ("ice: base subfunction aux driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/6951d217-ac06-4482-a35d-15d757fd90a3@stanley.mountainSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/intel/ice/ice_sf_eth.c

@@ -108,9 +108,9 @@ static int ice_sf_dev_probe(struct auxiliary_device *adev,
 	vsi->flags = ICE_VSI_FLAG_INIT;
 
 	priv = ice_allocate_sf(&adev->dev, pf);
-	if (!priv) {
+	if (IS_ERR(priv)) {
 		dev_err(dev, "Subfunction devlink alloc failed");
-		return -ENOMEM;
+		return PTR_ERR(priv);
 	}
 
 	priv->dev = sf_dev;