drm/nouveau/nv46: Change mc subdev oclass from nv44 to nv4c

commit 0a363e85 upstream.

MSI interrupts appear to not work for nv46 based cards. Change the mc
subdev oclass for these cards from nv44 to nv4c, the nv4c mc code is
identical to the nv44 mc code except that it does not use msi
(it does not define a msi_rearm callback).

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=90435Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
[ luis: backported to 3.16:
  - file rename: drivers/gpu/drm/nouveau/nvkm/engine/device/nv40.c ->
    drivers/gpu/drm/nouveau/core/engine/device/nv40.c ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/nouveau/core/engine/device/nv40.c

@@ -265,7 +265,7 @@ nv40_identify(struct nouveau_device *device)
 		device->oclass[NVDEV_SUBDEV_CLOCK  ] = &nv40_clock_oclass;
 		device->oclass[NVDEV_SUBDEV_THERM  ] = &nv40_therm_oclass;
 		device->oclass[NVDEV_SUBDEV_DEVINIT] =  nv1a_devinit_oclass;
-		device->oclass[NVDEV_SUBDEV_MC     ] =  nv44_mc_oclass;
+		device->oclass[NVDEV_SUBDEV_MC     ] =  nv4c_mc_oclass;
 		device->oclass[NVDEV_SUBDEV_BUS    ] =  nv31_bus_oclass;
 		device->oclass[NVDEV_SUBDEV_TIMER  ] = &nv04_timer_oclass;
 		device->oclass[NVDEV_SUBDEV_FB     ] =  nv46_fb_oclass;