Staging: line6: remove spaces before commas.

Fix three space prohibited errors in pcm.h found by checkpatch.pl.

Signed-off-by: Jonas Lundqvist <jonas@gannon.se>
Reviewed-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>