FramebufferVk::resolveColorWithCommand() is currently using the wrong
mip level value by using the GL index value, rather than calculating the
VK value from (index value - the base level).

Bug: angleproject:4753
Test: FramebufferTest_ES31::MultisampleResolveIntoMipMapWithBlit()
Change-Id: I8ddaeb21c4957b46880f5ef5f6a78242c04b4dcd
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2349951Reviewed-by: Charlie Lao <cclao@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>