Don't resume after call ends until gain audio focus

this patch can fix below two issues.
1) after call ends, telephony will still play call end tone.
so we should not resume fm immediately after call ends.
2) if fm has been paused and abandoned audiofocus because
other video app starts to play and sends pause cmd to fm,
then after call ends, we should not resume fm automatically.

we should only resmue fm after fm gains audio focus.

Change-Id: I729ac3e92512ff43368494ecde87d3d9f8dfe2c6
CRs-Fixed: 1110621