LU-9859 lnet: fold lprocfs_call_handler functionality into lnet_debugfs_*

LU-9859 lnet: fold lprocfs_call_handler functionality into lnet_debugfs_*

The calling convention for ->proc_handler is rather clumsy,
as a comment in fs/procfs/proc_sysctl.c confirms.
lustre has copied this convention to lnet_debugfs_{read,write},
and then provided a wrapper for handlers - lprocfs_call_handler -
to work around the clumsiness.

It is cleaner to just fold the functionality of lprocfs_call_handler()
into lnet_debugfs_* and let them call the final handler directly.

If these files were ever moved to /proc/sys (which seems unlikely) the
handling in fs/procfs/proc_sysctl.c would need to be fixed to, but
that would not be a bad thing.

So modify all the functions that did use the wrapper to not need it
now that a more sane calling convention is available.

Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Change-Id: I548ed6a3179cdb7cd5c024febd3fee4709285a82
Reviewed-on: https://review.whamcloud.com/44309
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>