drm/radeon/kms: fix vram setup on rs600

also fix up rs690 mem width.

should fix fdo bug 25408

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rs690.c b/drivers/gpu/drm/radeon/rs690.c
index e7a5f87..81b8efc 100644
--- a/drivers/gpu/drm/radeon/rs690.c
+++ b/drivers/gpu/drm/radeon/rs690.c
@@ -131,19 +131,13 @@
 
 void rs690_vram_info(struct radeon_device *rdev)
 {
-	uint32_t tmp;
 	fixed20_12 a;
 
 	rs400_gart_adjust_size(rdev);
 	/* DDR for all card after R300 & IGP */
 	rdev->mc.vram_is_ddr = true;
-	/* FIXME: is this correct for RS690/RS740 ? */
-	tmp = RREG32(RADEON_MEM_CNTL);
-	if (tmp & R300_MEM_NUM_CHANNELS_MASK) {
-		rdev->mc.vram_width = 128;
-	} else {
-		rdev->mc.vram_width = 64;
-	}
+	rdev->mc.vram_width = 128;
+
 	rdev->mc.real_vram_size = RREG32(RADEON_CONFIG_MEMSIZE);
 	rdev->mc.mc_vram_size = rdev->mc.real_vram_size;