Fixes interaction with ImageInstruction rework in previous patch

Bug: b/129523279
Test: dEQP-VK.image.*
Change-Id: I3c0ff7d4497f95f67dc9fc08ad8793f81f7c5f2c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30228Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>