Handled DSSA use case for xmm7modem. Added driver function
to switch between available card slots for SIM.
Only one SIM will be active at a given time. On calling this
function the active SIM will be removed and the card slot made
inactive and SIM in the other card slot will be made active.
Use case is similar to a SIM swap/change where one SIM is replaced
another SIM in the same slot.