drm/radeon: allow selection of alignment in the sub-allocator

There are cases where we need more than 4k alignment.  No
functional change with this commit.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 7b7d23a..82e8e36 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -455,6 +455,7 @@
 	uint64_t		gpu_addr;
 	void			*cpu_ptr;
 	uint32_t		domain;
+	uint32_t		align;
 };
 
 struct radeon_sa_bo;