Vulkan: Fix counting for shader texture bindings. Vulkan prefers to use a single binding for each texture array. Previously we were reserving binding space for array elements. Doesn't immediately fix any tests but allows more tests to pass in subsequent CLs. Bug: angleproject:2494 Change-Id: I238d4e6f491bfa6daf04dde24f8111c8418cd59c Reviewed-on: https://chromium-review.googlesource.com/1101570 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org> Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>