ANDROID: GKI: net: remove conditional members causing ABI diffs

Remove conditions for including struct net members based on kernel configs
CONFIG_IP_SCTP, CONFIG_NETFILTER_FAMILY_BRIDGE and
CONFIG_BRIDGE_NF_EBTABLES.

Bug: 151115806
Test: build
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I6b0e75f0976ab79ea933fe64bc73ba08c9e7c71a