drm/exynos: plane: honor buffer offset for dma_addr

Previously we were ignoring the buffer offsets that are
passed through the addfb2 ioctl. This didn't cause any
major issues, since for uni-planar formats (like XRGB8888)
userspace would most of the time just use offsets[0]=0.

However with NV12 offsets[1] is very likely non-zero.
So properly apply the offsets to our dma addresses.

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Acked-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_plane.c

@@ -76,7 +76,7 @@ int exynos_check_plane(struct drm_plane *plane, struct drm_framebuffer *fb)
 			return -EFAULT;
 		}
 
-		exynos_plane->dma_addr[i] = buffer->dma_addr;
+		exynos_plane->dma_addr[i] = buffer->dma_addr + fb->offsets[i];
 
 		DRM_DEBUG_KMS("buffer: %d, dma_addr = 0x%lx\n",
 				i, (unsigned long)exynos_plane->dma_addr[i]);