ALSA: usb-audio: US16x08: Initialize array before use

ALSA: usb-audio: US16x08: Initialize array before use

Initialize meter_urb array before use in mixer_us16x08.c.

CID 1410197: (#1 of 1): Uninitialized scalar variable (UNINIT)
uninit_use_in_call: Using uninitialized value *meter_urb when
calling get_meter_levels_from_urb.

Coverity Link:
https://scan7.scan.coverity.com/#/project-view/52849/11354?selectedIssue=1410197

Fixes: d2bb390a2081 ("ALSA: usb-audio: Tascam US-16x08 DSP mixer quirk")
Signed-off-by: Tanya Agarwal <tanyaagarwal25699@gmail.com>
Link: https://patch.msgid.link/20241229060240.1642-1-tanyaagarwal25699@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>