st/mesa: remove asserts in st_texture_image_copy

This is for 7.10 only. The fix in master looks too complex to be
cherry-picked.

The assertions fail when generating mipmaps for NPOT textures.

This fixes:
- fbo-generatemipmap-formats

Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/state_tracker/st_texture.c

@@ -285,10 +285,6 @@ st_texture_image_copy(struct pipe_context *pipe,
    struct pipe_box src_box;
    GLuint i;
 
-   assert(u_minify(src->width0, srcLevel) == width);
-   assert(u_minify(src->height0, srcLevel) == height);
-   assert(u_minify(src->depth0, srcLevel) == depth);
-
    src_box.x = 0;
    src_box.y = 0;
    src_box.width = width;