msix: allow qword MSI-X table accesses

PCI spec says:

For all accesses to MSI-X Table and MSI-X PBA fields, software must use
aligned full DWORD or aligned full QWORD transactions; otherwise, the
result is undefined.

However, since MSI-X was converted to use memory API, QEMU
started blocking qword transactions, only allowing DWORD
ones. Guests do not seem to use QWORD accesses, but let's
be spec compliant.

Fixes: 95524ae8dc ("msix: convert to memory API")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/pci/msix.c

@@ -199,6 +199,9 @@ static const MemoryRegionOps msix_table_mmio_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
     .valid = {
         .min_access_size = 4,
+        .max_access_size = 8,
+    },
+    .impl = {
         .max_access_size = 4,
     },
 };
@@ -227,6 +230,9 @@ static const MemoryRegionOps msix_pba_mmio_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
     .valid = {
         .min_access_size = 4,
+        .max_access_size = 8,
+    },
+    .impl = {
         .max_access_size = 4,
     },
 };