[ALSA] Fix check of enable module option

Fix the check of enable module option in probe of platform_device drivers.
It shouldn't break the loop but just ignore if enable[i] is false.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/drivers/mpu401/mpu401.c b/sound/drivers/mpu401/mpu401.c
index 915589a..9d10d79 100644
--- a/sound/drivers/mpu401/mpu401.c
+++ b/sound/drivers/mpu401/mpu401.c
@@ -240,8 +240,10 @@
 		return err;
 
 	devices = 0;
-	for (i = 0; i < SNDRV_CARDS && enable[i]; i++) {
+	for (i = 0; i < SNDRV_CARDS; i++) {
 		struct platform_device *device;
+		if (! enable[i])
+			continue;
 #ifdef CONFIG_PNP
 		if (pnp[i])
 			continue;