ipa_keepalive_fsm: Suppress error messages for INIT -> INIT transition
ipa_keepalive_fsm: Suppress error messages for INIT -> INIT transition

If we receive an OSMO_IPA_KA_E_STOP in INIT state, we are trying to
re-enter INIT, which is not permitted as per the FSM definition.

Adding this permission avoids the below error message from hitting the
logs every time this happens:

<0003> input/ipa_keepalive.c:158 IPA-KEEPALIVE(server)[0x612000000520]{INIT}: transition to state INIT not permitted!

Change-Id: I8db2f2e708fc4fbb81f5019973098a80e8f540d2

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