st/readpixels: fix accel path for skipimages.
st/readpixels: fix accel path for skipimages.

We don't need to use the 3d image address here as that will
include SKIP_IMAGES, and we are only blitting a single
2D anyways, so just use the 2D path.

This fixes some memory overruns under CTS
 packed_pixels.packed_pixels_pixelstore when PACK_SKIP_IMAGES
is used.

Cc: "11.0" <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Reviewed-by: Iago Toral Quiroga <a847aabaac44184372f6b1cd1a59aa254daaeb0b@igalia.com>
Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler