firewire: cdev: fix potential leak of kernel stack due to uninitialized value

Recent change brings potential leak of value on kernel stack to userspace
due to uninitialized value.

This commit fixes the bug.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: baa914c ("firewire: add kernel API to access CYCLE_TIME register")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20220512112037.103142-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: takaswie

drivers/firewire/core-cdev.c

@@ -1211,7 +1211,7 @@ static int ioctl_get_cycle_timer2(struct client *client, union ioctl_arg *arg)
 	struct fw_cdev_get_cycle_timer2 *a = &arg->get_cycle_timer2;
 	struct fw_card *card = client->device->card;
 	struct timespec64 ts = {0, 0};
-	u32 cycle_time;
+	u32 cycle_time = 0;
 	int ret = 0;
 
 	local_irq_disable();