PCI/MSI: Return failure when msix_setup_entries() fails

If alloc_msi_entry() fails, we free resources and set ret = -ENOMEM.

However, msix_setup_entries() returns 0 unconditionally.  Return the error
code instead.

Fixes: e75eafb9 ("genirq/msi: Switch to new irq spreading infrastructure")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>