alsa_sound: reset "mVoipMicMute" in close streams

-When phone is in hold state,both input and output streams
 will be closed. And when in unhold state, openOutput and
 openinputstream is called and reset "mVoipMicMute" to
 false.
-Fix is to remove resetting of "mVoipMicMute" flag in openInput
 This flag is already being in reset in closeInput.

 CRs-Fixed: 525323

Change-Id: Ib48598a0ae78b5d5fa33635507b1639e45cec679