ALSA: Fix assignment of 0/1 to bool variables

Convert 0 to false and 1 to true when assigning values to bool
variables. Inspired by commit 3db1cd5c.

The simplified semantic patch that find this problem is as
follows (http://coccinelle.lip6.fr/

):

@@
bool b;
@@
(
-b = 0
+b = false
|
-b = 1
+b = true
)

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>