[FM] Sometimes FM icon will not appear in the notification bar after searching...

[FM] Sometimes FM icon will not appear in the notification bar after searching out stations in the background

Launch FM and play -> Search stations -> Tap "Home"
key and wait for searching out stations -> Repeat
step2~3 several times -> Check the notification bar
every time, sometimes FM icon will not appear in the
notification bar after searching out stations in the background.

The fix is to set mIsScanning false before notifying activity.

https://partner-android-review.git.corp.google.com/#/c/189364/



Bug 18760881

Change-Id: I46ae2e679d40b8200fbf52209ef79afe5bc3dc40
Signed-off-by: Benson Huang <benson.huang@mediatek.com>