LU-6142 lustre: remove some unnecessary code.

LU-6142 lustre: remove some unnecessary code.

The field 'targets_proc_entry' is never set, so remove it and all
reference to it.

lov_dump_pool() is never used, so remove it.

min_u64() is never used - remove it.

max_u64() is used, but 'min3()' from linux/kernel.h makes
the code clearer, so use that instead.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I3ed6abc1b23e611bd4a573fa78981955a494c344
Reviewed-on: https://review.whamcloud.com/39739
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>