[FM] There is no sound output after resuming playing when FM is over BT

Launch FM radio and play -> Stop FM -> Turn on BT and connect with BT
earphone with A2DP -> Open FM and resume playing, there is no sound
output after step 4.

Bug 19171819
from: https://partner-android-review.googlesource.com/#/c/199683/



Change-Id: I01d3975387840d9356c6f80d1f411eeb8526f930
Signed-off-by: Benson Huang <benson.huang@mediatek.com>