c9e0edc2 changed the layerCount in SubresourceUpdate to
VK_REMAINING_ARRAY_LAYERS in some cases. So that the deferred
clear logic cannot work correctly.

Bug: angleproject:4617
Change-Id: Idedada085c618ff900538094412c752522594684
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2191551Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Charlie Lao <cclao@google.com>