Use true/false for bool type return in uac_clock_source_is_valid().
Signed-off-by: Saurav Girepunje <saurav.girepunje@gmail.com>
Link: https://lore.kernel.org/r/20191029175200.GA7320@sauravSigned-off-by: Takashi Iwai <tiwai@suse.de>