minigbm: i915: fix planar height alignment

Aligned planar height should be calculated from the planar height, not
the buffer height.

BUG=b:133292033
TEST=ArcVideoTest renders video correctly (w/a few other changes)

Change-Id: I1dc35ab4eebf9a5a86b2a9befaeb817a56dcfec2
Reviewed-on: https://chromium-review.googlesource.com/1824304
Tested-by: David Stevens <stevensd@chromium.org>
Commit-Ready: Tomasz Figa <tfiga@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
diff --git a/i915.c b/i915.c
index 1a51aa4..ec0d8fd 100644
--- a/i915.c
+++ b/i915.c
@@ -256,7 +256,7 @@
 		break;
 	}
 
-	*aligned_height = ALIGN(bo->meta.height, vertical_alignment);
+	*aligned_height = ALIGN(*aligned_height, vertical_alignment);
 	if (i915->gen > 3) {
 		*stride = ALIGN(*stride, horizontal_alignment);
 	} else {