minigbm: format_modifiers[0] -> format_modifier

The early version of the modifier assumed per plane modifiers.
The current version is only one modifier per buffer object.

BUG=none
TEST=compile

Change-Id: Ic3899118d44cb172ee2e4eae346e98cdf8328cf9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/2654590
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Commit-Queue: Gurchetan Singh <gurchetansingh@chromium.org>
diff --git a/drv.h b/drv.h
index 4a47b76..50ff6ab 100644
--- a/drv.h
+++ b/drv.h
@@ -85,7 +85,7 @@
 	int fds[DRV_MAX_PLANES];
 	uint32_t strides[DRV_MAX_PLANES];
 	uint32_t offsets[DRV_MAX_PLANES];
-	uint64_t format_modifiers[DRV_MAX_PLANES];
+	uint64_t format_modifier;
 	uint32_t width;
 	uint32_t height;
 	uint32_t format;
@@ -166,7 +166,7 @@
 
 uint32_t drv_bo_get_plane_stride(struct bo *bo, size_t plane);
 
-uint64_t drv_bo_get_plane_format_modifier(struct bo *bo, size_t plane);
+uint64_t drv_bo_get_format_modifier(struct bo *bo);
 
 uint32_t drv_bo_get_format(struct bo *bo);