LU-13308 mdc: support additional flags for OBD_IOC_CHLG_POLL ioctl

LU-13308 mdc: support additional flags for OBD_IOC_CHLG_POLL ioctl

Currently the mdc kernel code expects the flag argument for
OBD_IOC_CHLG_POLL ioctl to only be CHANGELOG_FLAG_FOLLOW. With
IPv6 we need to send a request to the kernel to present the NID
in the struct lnet_nid format since we can't just send large NIDs
to user land if we are using older tools.

With the newer user land tools we will be sending an expanded flag
which the current kernel changelog code can't handle. Rework the
code to support the new flag if we end up with the case of newer
user land tools and an older kernel. This code will also maintain
backwards compatiblity with the older user land tools.

Change-Id: I26a80d30ce2ebf2075a2a8f510ff81d6b0b8d848
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/52361
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Etienne AUJAMES <eaujames@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>