IPsec: duplicate sysctls

[Maxime Villard <max%m00nbsd.net@localhost>]

As Ryota Ozaki noted a week ago, there are several duplicate sysctls

	net.inet.esp.trans_deflev = net.inet.ipsec.esp_trans_deflev
	net.inet.esp.net_deflev   = net.inet.ipsec.esp_net_deflev
	net.inet.ah.cleartos      = net.inet.ipsec.ah_cleartos
	net.inet.ah.offsetmask    = net.inet.ipsec.ah_offsetmask
	net.inet.ah.trans_deflev  = net.inet.ipsec.ah_trans_deflev
	net.inet.ah.net_deflev    = net.inet.ipsec.ah_net_deflev

Under net.inet6 there are no duplicates, we use the convention on the
right here.

But I believe the one on the left is the best one. I guess it is fine to
switch everything to the left one and remove the duplicates?

Maxime