isl/state: Use TILEWALK_XMAJOR for linear surfaces on gen7

This matches better what happens on gen8 where the "Tiled Surface" and
"Tile Walke" bits are combined into a single two-bit value.  This is also
more consistent with what the GL driver does.

Reviewed-by: Chad Versace <chad.versace@intel.com>
Cc: "12.0" <mesa-stable@lists.freedesktop.org>

src/intel/isl/isl_surface_state.c

@@ -328,8 +328,8 @@ isl_genX(surf_fill_state_s)(const struct isl_device *dev, void *state,
    s.TileMode = isl_to_gen_tiling[info->surf->tiling];
 #else
    s.TiledSurface = info->surf->tiling != ISL_TILING_LINEAR,
-   s.TileWalk = info->surf->tiling == ISL_TILING_X ? TILEWALK_XMAJOR :
-                                                     TILEWALK_YMAJOR;
+   s.TileWalk = info->surf->tiling == ISL_TILING_Y0 ? TILEWALK_YMAJOR :
+                                                      TILEWALK_XMAJOR,
 #endif
 
 #if GEN_GEN >= 8