Supress SIM_STATE_UNKNOWN when not PERSOSUBSTATE_SIM_NETWORK

During APPSTATE_SUBSCRIPTION_PERSO, we don't know if SIM locked or not
before PERSOSUBSTATE_SIM_NETWORK. Setting SIM state UNKNOWN on
APPSTATE_SUBSCRIPTION_PERSO with other substate introduces uncessary SIM
state transition. It's OK to just keep the last SIM state (NOT_READY,for
example, the initial state during phone bootup).

Also fixed import.

Test: make
Change-Id: I89d479a51c81fe25713f3694f640e2eead1888cd