ionic: Fix an error code in ionic_lif_alloc()

We need to set the error code on this path.  Otherwise it probably
results in a NULL dereference down the line.

Fixes: aa319881 ("ionic: Add RSS support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>