etnaviv: Disable seamless cube map on GC880

etnaviv: Disable seamless cube map on GC880

The GC880 on iMX6DL indicates in it's minorFeatures2 register that it
does support SEAMLESS_CUBE_MAP, however when the TE.SAMPLER_CONFIG1
VIVS_TE_SAMPLER_CONFIG1_SEAMLESS_CUBE_MAP bit is set on GC880 on iMX6DL,
the result is corrupted image. In particular, the following ~112 dEQPs
are affected and fail:

  dEQP-GLES2.functional.texture.filtering.cube.*

This only happens on MX6DL GC880, MX6Q GC2000 and STM32MP1 GC400(GCnano)
do not report the minorFeatures2 SEAMLESS_CUBE_MAP bit and ignore the
TE_SAMPLER_CONFIG1 VIVS_TE_SAMPLER_CONFIG1_SEAMLESS_CUBE_MAP bit (note
that ss->seamless_cube_map is unconditionally set by mesa at times even
PIPE_CAP_SEAMLESS_CUBE_MAP_PER_TEXTURE returns 0), so there is no visible
problem and there are no failing dEQP tests on the GC2000 and GCnano.

This might imply that the minorFeatures2 SEAMLESS_CUBE_MAP has some
different meaning on GC880 or the SEAMLESS_CUBE_MAP behaves differently
on the GC880.

This patch does not set the SEAMLESS_CUBE_MAP bit on hardware which does
not indicate support for seamless cube map and on GC880, which results
in reduction in failed dEQPs: 635 to 186 on GC880, 274 to 270 on GC2000
and no change on GC400(GCnano).

Fixes: 8dd26fa2f06 ("etnaviv: support GL_ARB_seamless_cubemap_per_texture")
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4865>