broadcom/vc4: Skip BO labeling when in simulator mode.

It was calling down into i915 trying to label the BO, which is definitely
not the right thing.

src/gallium/drivers/vc4/vc4_bufmgr.c

@@ -69,7 +69,7 @@ vc4_bo_label(struct vc4_screen *screen, struct vc4_bo *bo, const char *fmt, ...)
                 .len = strlen(name),
                 .name = (uintptr_t)name,
         };
-        drmIoctl(screen->fd, DRM_IOCTL_VC4_LABEL_BO, &label);
+        vc4_ioctl(screen->fd, DRM_IOCTL_VC4_LABEL_BO, &label);
 
         ralloc_free(name);
 }

src/gallium/drivers/vc4/vc4_simulator.c

@@ -654,6 +654,10 @@ vc4_simulator_ioctl(int fd, unsigned long request, void *args)
                  */
                 return 0;
 
+        case DRM_IOCTL_VC4_LABEL_BO:
+                /* This is just debug information, nothing to do. */
+                return 0;
+
         case DRM_IOCTL_VC4_GET_TILING:
         case DRM_IOCTL_VC4_SET_TILING:
                 /* Disable these for now, since the sharing with i965 requires