UPSTREAM: ALSA: timer: Fix leak in SNDRV_TIMER_IOCTL_PARAMS

(cherry pick from commit cec8f96e)

The stack object “tread” has a total size of 32 bytes. Its field
“event” and “val” both contain 4 bytes padding. These 8 bytes
padding bytes are sent to user without being initialized.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Bug: 28980557
Change-Id: I6e4220b42c8370b060f5fd7f0500d39655ac4850