S24_LE format fix in aml soc sound driver

Error in bitwise manipulation for S24_LE format : 24 bits samples have to be right-shifted into hw buffer 32 bits words.
Those soc are perfectly capable of 24bits sound playback. At least MX2 is also capable of 192khz sound playback, provided it is not restricted in 1/ ALSA asound.conf (board/amlogic/mx2ref/overlay/etc/asound.conf) 2/ the media player (see xbmc/cores/AudioEngine/Sinks/AESinkALSA.cpp:275).