libstagefright: Changing frames per sample from 1 to maximum in damr atom

-A clip encoded with AMR audio format on SF does not play in
another phone
-Frames per sample is incorrect in the encoded clip as we read
10 frames in single audio HAL read.
-Changing frames per sample to 15 (maximum frames per sample)
in damr atom of encoded clip.

Change-Id: I029bee7f6a9689e7664aa7c30ef09a40579f317a

CRs-Fixed: 282514