Creating sRGB views was conditioned to
VK_IMAGE_CREATE_MUTABLE_FORMAT_BIT being necessary, but that flag can be
set for reasons other than sRGB override, such as when recreating the
image to be used as a storage image.

Bug: angleproject:4551
Change-Id: I6f94a1c898b599d4333d74608c7451b4ce4f71f0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2279134Reviewed-by: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>