anv/genX: Solve the vkCreateGraphicsPipelines crash

The crash is due to NULL pColorBlendState, which is legal if the
pipeline has rasterization disabled or if the subpass of the render pass
the pipeline is created against does not use any color attachments.

Test: Sample subpasses from LunarG can run without crash

Signed-off-by: Xu,Randy <randy.xu@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Cc: "17.0 13.0" <mesa-stable@lists.freedesktop.org>
(cherry picked from commit 57595cb0739d50a3fbd0841d7475bd775f3e24f3)
1 file changed