drm/nouveau: pull refclk from vbios on limits 0x40 boards

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_bios.c

@@ -5049,11 +5049,7 @@ int get_pll_limits(struct drm_device *dev, uint32_t limit_match, struct pll_lims
 		pll_lim->vco1.max_n = record[11];
 		pll_lim->min_p = record[12];
 		pll_lim->max_p = record[13];
-		/* where did this go to?? */
-		if ((entry[0] & 0xf0) == 0x80)
-			pll_lim->refclk = 27000;
-		else
-			pll_lim->refclk = 100000;
+		pll_lim->refclk = ROM16(entry[9]) * 1000;
 	}
 
 	/*