drm/nv4c/mc: disable msi

Several users have, over time, reported issues with MSI on these IGPs.
They're old, rarely available, and MSI doesn't provide such huge
advantages on them. Just disable.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87361
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74492
Fixes: fa8c9ac ("drm/nv4c/mc: nv4x igp's have a different msi rearm register")
Cc: stable@vger.kernel.org
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/subdev/mc/nv4c.c

@@ -24,13 +24,6 @@
 
 #include "nv04.h"
 
-static void
-nv4c_mc_msi_rearm(struct nouveau_mc *pmc)
-{
-	struct nv04_mc_priv *priv = (void *)pmc;
-	nv_wr08(priv, 0x088050, 0xff);
-}
-
 struct nouveau_oclass *
 nv4c_mc_oclass = &(struct nouveau_mc_oclass) {
 	.base.handle = NV_SUBDEV(MC, 0x4c),
@@ -41,5 +34,4 @@ nv4c_mc_oclass = &(struct nouveau_mc_oclass) {
 		.fini = _nouveau_mc_fini,
 	},
 	.intr = nv04_mc_intr,
-	.msi_rearm = nv4c_mc_msi_rearm,
 }.base;