call: fix mute microphone

When call unpaused after microphone was muted, mute state changes to
unmute in call, when in audio input it still muted. After this all attempts
to mute/unmute audio are unsuccessful. This patch removes
mute state update when restarting media, since audio muting managed only
by audio input, and should not be related of rtp session parameters.
This patch left video mute state updates.

Change-Id: I4ac3bea04865fa23b876d5c10fcb5c172c4501a3