LU-6142 lnet: discard unused lnet_print_hdr()

LU-6142 lnet: discard unused lnet_print_hdr()

lnet_print_hdr() is unused, and has not been used in git history since
at least 2004.
So remove it.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I0d72726b69f205a8c62ae4dbf1423f6e745db5fe
Reviewed-on: https://review.whamcloud.com/39358
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>