Fix a couple of checkpatch.pl issues

  ERROR: space required before the open parenthesis '('
  #129: FILE: pcm.c:125:
  +       switch(rate) {

  WARNING: braces {} are not necessary for single statement blocks
  #419: FILE: pcm.c:415:
  +               if (!rt->playback.instance) {
  +                       hiface_pcm_stream_stop(rt);
  +               }

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>