etnaviv: Limit max line width to 1.0 on GPUs needing wide line emulation

The HW line rasterizer on some Vivante GPUs doesn't produce
spec-conformant results for wide lines. Correct emulation via
triangle expansion is complex and interacts poorly with features
like primitive IDs, shader side effects (SSBOs, atomics), and
varying interpolation.

Rather than carrying fragile emulation, limit the advertised
max line width to 1.0 on affected GPUs. The GLES3 spec only
requires support for width 1.0, so this doesn't affect conformance.

Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
Reviewed-by: Daniel Lang <dalang@gmx.at>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40006>

src/etnaviv/ci/etnaviv-gc7000-r6214-fails.txt

@@ -1,5 +1,4 @@
 dEQP-GLES2.functional.fbo.completeness.renderable.texture.color0.rgb_half_float_oes,Fail
-dEQP-GLES2.functional.rasterization.primitives.lines_wide,Fail
 dEQP-GLES2.functional.shaders.operator.selection.highp_float_fragment,Fail
 dEQP-GLES2.functional.shaders.operator.selection.highp_int_fragment,Fail
 dEQP-GLES2.functional.shaders.operator.selection.highp_ivec2_fragment,Fail

src/gallium/drivers/etnaviv/etnaviv_screen.c

@@ -359,6 +359,8 @@ etna_init_screen_caps(struct etna_screen *screen)
 
    caps->max_line_width =
    caps->max_line_width_aa =
+      VIV_FEATURE(screen, ETNA_FEATURE_WIDELINE_TRIANGLE_EMU) ? 1.0f : 8192.0f;
+
    caps->max_point_size =
    caps->max_point_size_aa = 8192.0f;