ALSA: pcm: playback silence - remove extra code

The removed condition handles de facto only one situation where
runtime->silence_filled variable is equal to runtime->buffer_size,
because this variable cannot go over the buffer size. This case is
implicitly caught by the required comparison of the noise distance
with the threshold.

Suggested-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230505155244.2312199-4-oswald.buddenhagen@gmx.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>