alsa_sound: Fix to avoid crash while erasing item from mDeviceList

-In AudioHardwareALSA's destructor,while erasing item from mDeviceList
is leading to crash in current implementation, if List containing
more than one item.
-This is happening because of Invalid iterator value after deleting
current item from List, then using same iterator for next operation.
-It can avoid returning an Iterator item form List's erase function
and then use it for next operation.

Change-Id: I4f440fe4b76ecf865cae1a2fd7edb1a37c9e9386
CRs-Fixed: 517101