drm/nouveau/bios/ramcfg: fix missing parentheses when calculating RON

Currently, the expression for calculating RON is always going to result
in zero no matter the value of ram->mr[1] because the ! operator has
higher precedence than the shift >> operator.  I believe the missing
parentheses around the expression before appying the ! operator will
result in the desired result.

[ Note, not tested ]

Detected by CoveritScan, CID#1324005 ("Operands don't affect result")

Fixes: c25bf7b6 ("drm/nouveau/bios/ramcfg: Separate out RON pull value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/fb/gddr3.c

@@ -87,7 +87,7 @@ nvkm_gddr3_calc(struct nvkm_ram *ram)
 		WR  = (ram->next->bios.timing[2] & 0x007f0000) >> 16;
 		/* XXX: Get these values from the VBIOS instead */
 		DLL = !(ram->mr[1] & 0x1);
-		RON = !(ram->mr[1] & 0x300) >> 8;
+		RON = !((ram->mr[1] & 0x300) >> 8);
 		break;
 	default:
 		return -ENOSYS;