radeon: Add missing swrast field initialization.

This is the equivalent of intel's
80513ec8b4.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/drivers/dri/radeon/radeon_texture.c

@@ -120,6 +120,9 @@ radeonAllocTextureImageBuffer(struct gl_context *ctx,
 	}
 	assert(!image->base.ImageOffsets);
 	image->base.ImageOffsets = malloc(slices * sizeof(GLuint));
+
+	_swrast_init_texture_image(timage);
+
 	teximage_assign_miptree(rmesa, texobj, timage);
 				
 	return GL_TRUE;