Add new Card Unavailable reason for SIM power down in APM.

REASON_APM_SIM_POWER_DOWN value added to CardUnavailableReason enum.
This is to indicate card absent event received when SIM is powered
down in APM.

Change-Id: I985e06d629715ebc0489a2fb19e908ab652bfeeb
CRs-Fixed: 661325