android: vulkan/util: add vk_descriptors.{c,h} to Makefile.sources

android: vulkan/util: add vk_descriptors.{c,h} to Makefile.sources

Fixes the following building errors:

FAILED: out/target/product/x86_64/obj/SHARED_LIBRARIES/vulkan.radv_intermediates/LINKED/vulkan.radv.so
...
ld.lld: error: undefined symbol: vk_create_sorted_bindings
>>> referenced by radv_descriptor_set.c:158 (external/mesa/src/amd/vulkan/radv_descriptor_set.c:158)
...
ld.lld: error: undefined symbol: vk_create_sorted_bindings
>>> referenced by radv_descriptor_set.c:340 (external/mesa/src/amd/vulkan/radv_descriptor_set.c:340)

Fixes: ad241b15a9e5 ("vk: consolidate dynamic descriptor binding sorting")
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9766>