alx: fix fallback to msi or legacy interrupts

If requesting msi-x interrupts fails we should fall back to msi or
legacy interrupts. However alx_realloc_ressources don't call
alx_init_intr, so we fail to set the right number of tx queues.
This results in watchdog timeouts and a nonfunctional adapter.

Fixes: d768319c

 ("alx: enable multiple tx queues")
Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>