isl: Mark A4B4G4R4_UNORM as supported on gen8

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Cc: "13.0" <mesa-dev@lists.freedesktop.org>
diff --git a/src/intel/isl/isl_format.c b/src/intel/isl/isl_format.c
index 98806f4..43c2f4f 100644
--- a/src/intel/isl/isl_format.c
+++ b/src/intel/isl/isl_format.c
@@ -217,7 +217,10 @@
    SF(50, 50,  x,  x,  x,  x,  x,  x,  x,    x,   P8A8_UNORM_PALETTE0)
    SF(50, 50,  x,  x,  x,  x,  x,  x,  x,    x,   P8A8_UNORM_PALETTE1)
    SF( x,  x,  x,  x,  x,  x,  x,  x,  x,    x,   A1B5G5R5_UNORM)
-   SF(90, 90,  x,  x, 90,  x,  x,  x,  x,    x,   A4B4G4R4_UNORM)
+   /* According to the PRM, A4B4G4R4_UNORM isn't supported until Sky Lake
+    * but empirical testing indicates that it works just fine on Broadwell.
+    */
+   SF(80, 80,  x,  x, 80,  x,  x,  x,  x,    x,   A4B4G4R4_UNORM)
    SF(90,  x,  x,  x,  x,  x,  x,  x,  x,    x,   L8A8_UINT)
    SF(90,  x,  x,  x,  x,  x,  x,  x,  x,    x,   L8A8_SINT)
    SF( Y,  Y,  x, 45,  Y,  Y,  Y,  x,  x,    x,   R8_UNORM)