ipa: Simplify code in ipa_server_conn_read
ipa: Simplify code in ipa_server_conn_read

By doing this change we remove a duplicated error code path and thus
avoid having to maintain an extra code path with function pointers.

Change-Id: I5bce9f92209cc2fb37b78792e34f7898c71d2327

osmocom/libosmo-abis,osmocom/libosmo-abis,osmocom/libosmo-abis