sm501: Update screen on frame buffer address change

When the guest changes the address of the frame buffer we need to
refresh the screen to correctly display the new content. This fixes
display update problems when changing between screens on AmigaOS.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/display/sm501.c

@@ -1235,6 +1235,7 @@ static void sm501_disp_ctrl_write(void *opaque, hwaddr addr,
         if (value & 0x8000000) {
             qemu_log_mask(LOG_UNIMP, "Panel external memory not supported\n");
         }
+        s->do_full_update = true;
         break;
     case SM501_DC_PANEL_FB_OFFSET:
         s->dc_panel_fb_offset = value & 0x3FF03FF0;
@@ -1298,6 +1299,7 @@ static void sm501_disp_ctrl_write(void *opaque, hwaddr addr,
         if (value & 0x8000000) {
             qemu_log_mask(LOG_UNIMP, "CRT external memory not supported\n");
         }
+        s->do_full_update = true;
         break;
     case SM501_DC_CRT_FB_OFFSET:
         s->dc_crt_fb_offset = value & 0x3FF03FF0;