Vulkan: Fix float16 use on devices without float16 support + fix subgroup_size_control validation error#11161

0cc4m merged 2 commits intomasterggml-org/llama.cpp:masterfrom

0cc4m/vulkan-fix-float16-validationggml-org/llama.cpp:0cc4m/vulkan-fix-float16-validationCopy head branch name to clipboard