The value string array that explain the type of the AMR DTX / SID
frames is incomplete, lets add the missing strings.
Change-Id: If9e80b4bd8bdc31323c7c276155b2538e20a99be
Related: OS#2978
gsm0503_coding contains AMR decoder functions for HR and FR. Those can
only decode AMR payload frames but not amr DTX frames. Lets add
functionality to detect DTX frames. Also lets add decoding for SID_UPDATE
frames as well as error checking for the SID frame recognition patterns.
Related: OS#2978
Change-Id: I2bbdb39ea20461ca08b2e6f1a33532cb55cd5195