The descriptor set resource counts for monolithic programs already have
all of the counts combined for all shader stages, rather than needing to
loop through and combine them all like program pipeline objects.

Bug: angleproject:3570
Test: CQ
Change-Id: Ib8a2fe7af991a8d9d5edcef346352c7bac0703fd
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2375869Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>