msi: Invoke msi/msix_write_config from PCI core

Also this functions is better invoked by the core than by each and every
device. This allows to drop the config_write callbacks from ich and
intel-hda.

CC: Alexander Graf <agraf@suse.de>
CC: Gerd Hoffmann <kraxel@redhat.com>
CC: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/msi.c

diff --git a/hw/msi.c b/hw/msi.c
index da12f33..556c7c4 100644
--- a/hw/msi.c
+++ b/hw/msi.c
@@ -264,7 +264,7 @@
     stl_le_phys(address, data);
 }
 
-/* call this function after updating configs by pci_default_write_config(). */
+/* Normally called by pci_default_write_config(). */
 void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));