Remove VK_KHR_16bit_storage support
Remove VK_KHR_16bit_storage support

This extension was never actually implemented. While it has been
promoted to 'core' in Vulkan 1.1, the storageBuffer16BitAccess feature
bit indicates whether or not the implementation supports the
functionality.

Bug: b/162742397
Test: dEQP-VK.info.device_mandatory_features
Change-Id: I3e2871ce09975db3da2ad1f042d6955dbd565479
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/47408
Kokoro-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Tested-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Reviewed-by: Sean Risser <2d04e98eeaa433fb55534399ab3ab2c06fdf7967@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,google/swiftshader