linux-yocto/5.15: ltp and squashfs fixes

Integrating the following commit(s) to linux-yocto/5.15:

    1c5699ee85d4 fs: move S_ISGID stripping into the vfs_*() helpers
    838f5d0701d8 fs: add mode_strip_sgid() helper
    d97172683641 squashfs: provide backing_dev_info in order to disable read-ahead

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 474ddb75)
Signed-off-by: Steve Sakoman <steve@sakoman.com>