When "backup intent" is requested on the mount (e.g. backupuid or
backupgid mount options), the corresponding flag needs to be set
on opens of directories (and files) but was missing in some
places causing access denied trying to enumerate and backup
servers.

Fixes kernel bugzilla #200953
https://bugzilla.kernel.org/show_bug.cgi?id=200953

Reported-and-tested-by: <whh@rubrik.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>