i965: Ignore 'centroid' interpolation qualifier in case of persample shading

I missed this change in commit f5cfb4a. It fixes the incorrect
rendering caused in Dolphin Emulator.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73915

Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Tested-by: Markus Wick <wickmarkus@web.de>
Reviewed-by: Matt Turner <mattst88@gmail.com>

src/mesa/drivers/dri/i965/brw_wm.c

@@ -62,7 +62,8 @@ brw_compute_barycentric_interp_modes(struct brw_context *brw,
    for (attr = 0; attr < VARYING_SLOT_MAX; ++attr) {
       enum glsl_interp_qualifier interp_qualifier =
          fprog->InterpQualifier[attr];
-      bool is_centroid = fprog->IsCentroid & BITFIELD64_BIT(attr);
+      bool is_centroid = (fprog->IsCentroid & BITFIELD64_BIT(attr)) &&
+         !persample_shading;
       bool is_sample = (fprog->IsSample & BITFIELD64_BIT(attr)) ||
          persample_shading;
       bool is_gl_Color = attr == VARYING_SLOT_COL0 || attr == VARYING_SLOT_COL1;