libstagefright: Keep LOOPING/AUTO_LOOPING flag during teardown

-LOOPING/AUTO_LOOPING flag is cleared during audio teardown process,
 then stream can only be played once which is not expected
-copy the previous looping flags and restore them after reset_l()
 is called

Change-Id: I4435d2b1d4d82efb235fc8099efa7d9f3d6af2d2
CRs-Fixed: 681711