drm/radeon: Add local 'fb' variables

Add a local 'fb' variable to a few places to get rid of the
'crtc->primary->fb' stuff. Looks neater and helps me with my poor
coccinelle skills later.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479498793-31021-3-git-send-email-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index f5e84f4..984b35f 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -3225,13 +3225,19 @@ void r100_bandwidth_update(struct radeon_device *rdev)
 	radeon_update_display_priority(rdev);
 
 	if (rdev->mode_info.crtcs[0]->base.enabled) {
+		const struct drm_framebuffer *fb =
+			rdev->mode_info.crtcs[0]->base.primary->fb;
+
 		mode1 = &rdev->mode_info.crtcs[0]->base.mode;
-		pixel_bytes1 = rdev->mode_info.crtcs[0]->base.primary->fb->bits_per_pixel / 8;
+		pixel_bytes1 = fb->bits_per_pixel / 8;
 	}
 	if (!(rdev->flags & RADEON_SINGLE_CRTC)) {
 		if (rdev->mode_info.crtcs[1]->base.enabled) {
+			const struct drm_framebuffer *fb =
+				rdev->mode_info.crtcs[1]->base.primary->fb;
+
 			mode2 = &rdev->mode_info.crtcs[1]->base.mode;
-			pixel_bytes2 = rdev->mode_info.crtcs[1]->base.primary->fb->bits_per_pixel / 8;
+			pixel_bytes2 = fb->bits_per_pixel / 8;
 		}
 	}