ipv6: Remove hoplimit initialization to -1

The changes introduced with git-commit a02e4b7d ("ipv6: Demark default
hoplimit as zero.") missed to remove the hoplimit initialization. As a
result, ipv6_get_mtu interprets the return value of dst_metric_raw
(-1) as 255 and answers ping6 with this hoplimit.  This patche removes
the line such that ping6 is answered with the hoplimit value
configured via sysctl.

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>