ipvs: use indirect call wrappers

Use the new indirect call wrappers in IPVS when calling the TCP or UDP
protocol specific functions.
This avoids an indirect calls in IPVS, and reduces the performance
impact of the Spectre mitigation.

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>