[FM] Recording name is saved abnormally after discarding it in FM

Launch FM and play a channel without a name -> Start recording
-> Stop recording and discard it -> Reboot the device -> Check
the recording name in Play Music, FM recording named as "MMddyyyy_hhmmss"
displays in Play Music.

The fix is to delete FM recording file when discarding.

Bug 19059404
from: https://partner-android-review.googlesource.com/#/c/193717/



Change-Id: I37fa949c108af175131fd08d0bbac66ef1cf4daf
Signed-off-by: Benson Huang <benson.huang@mediatek.com>