https://gitlab.khronos.org/vulkan/vulkan/-/merge_requests/3399 clarified
that when identity component swizzle is expected, one can also use the
corresponding component enum.

Fixes: b/167706626
Change-Id: I2c94f6ac108be5269d56f397ecf3da58cd310e5e
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48168Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Sean Risser <srisser@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>