drm/nv40: make INIT_COMPUTE_MEM a NOP, just like nv50

It appears we aren't required to do memory sizing ourselves on nv40
either.  NV40 init tables read a strap from PEXTDEV_BOOT_0 into a
CRTC register, and then later use that value to select a memory
configuration (written to PFB_CFG0, just like INIT_COMPUTE_MEM on
earlier cards) with INIT_IO_RESTRICT_PROG.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_bios.c

@@ -1865,7 +1865,7 @@ init_compute_mem(struct nvbios *bios, uint16_t offset, struct init_exec *iexec)
 
 	struct drm_nouveau_private *dev_priv = bios->dev->dev_private;
 
-	if (dev_priv->card_type >= NV_50)
+	if (dev_priv->card_type >= NV_40)
 		return 1;
 
 	/*