etnaviv: Do not filter out PIPE_FORMAT_S8_UINT_Z24_UNORM on pre-HALTI2

etnaviv: Do not filter out PIPE_FORMAT_S8_UINT_Z24_UNORM on pre-HALTI2

The format PIPE_FORMAT_S8_UINT_Z24_UNORM is supported even on pre-HALTI
hardware like GCnano. Do not report it as unsupported format.

This fixes the following dEQP on GCnano:
dEQP-GLES2.functional.fbo.completeness.renderable.texture.color0.depth_stencil_unsigned_int_24_8

Fixes: 64c7cdcae51 ("etnaviv: add missing formats")
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3200>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3200>