netfilter: nf_ct_h323: fix usage of MODULE_ALIAS_NFCT_HELPER

ctnetlink uses the aliases that are created by MODULE_ALIAS_NFCT_HELPER
to auto-load the module based on the helper name. Thus, we have to use
RAS, Q.931 and H.245, not H.323.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>