lavapipe: fix templated descriptor updates
The template path was buggy but CTS only tested it with Vulkan 1.1 enabled. It was just missing the dstArrayElement offset. Fixes: 41f7fa27 ("lavapipe: add support for VK_KHR_descriptor_update_template") Reviewed-By:Mike Blumenkrantz <michael.blumenkrantz@gmail.com> Part-of: <mesa/mesa!9675>