panfrost: Fix logic ops on Bifrost

opaque should not be set when logicops are enabled, that needs blending
even on Bifrost. Fixes is for when I believe the bug became possible to hit.
The logical error is older.

Fixes Piglit logicop tests again.

Fixes: d849d9779a ("panfrost: Avoid blend shader when not blending")
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20685>

src/gallium/drivers/panfrost/pan_cmdstream.c

@@ -4209,7 +4209,7 @@ panfrost_create_blend_state(struct pipe_context *pipe,
       const bool supports_2src = pan_blend_supports_2src(PAN_ARCH);
       so->info[c] = (struct pan_blend_info){
          .enabled = (equation.color_mask != 0),
-         .opaque = pan_blend_is_opaque(equation),
+         .opaque = !blend->logicop_enable && pan_blend_is_opaque(equation),
          .constant_mask = constant_mask,
 
          /* TODO: check the dest for the logicop */

src/panfrost/lib/pan_blend.c

@@ -796,7 +796,8 @@ GENX(pan_blend_get_shader_locked)(const struct panfrost_device *dev,
    };
 
    /* Blend shaders should only be used for blending on Bifrost onwards */
-   assert(dev->arch <= 5 || !pan_blend_is_opaque(state->rts[rt].equation));
+   assert(dev->arch <= 5 || state->logicop_enable ||
+          !pan_blend_is_opaque(state->rts[rt].equation));
    assert(state->rts[rt].equation.color_mask != 0);
 
    struct hash_entry *he =