LU-14651 llite: extend inode methods with user namespace arg

LU-14651 llite: extend inode methods with user namespace arg

Kernel 5.12 supports idmapped mounts, which extends
vfsmount struct with a new struct user_namespace member,
and also extends some inode methods with an additional
user namespace argument.

The series can be found here:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=idmapped_mounts

Lustre-change: https://review.whamcloud.com/45938
Lustre-commit: 0feec5a3c7d4518d5c563739124b202a6a0a99f7

Change-Id: I7cccde8cb3288e1ce3d9b6255796b954a6e115df
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/46278
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>