ALSA: usb-audio: qcom: Initialize offload control return value

ALSA: usb-audio: qcom: Initialize offload control return value

snd_usb_offload_create_ctl() returns ret after walking the USB PCM list,
but ret is only assigned after a playback stream passes the endpoint and
PCM-index filters.

If all playback streams are skipped, for example because there is no
playback endpoint or because all PCM indexes exceed the 0xff control
range, the function returns an uninitialized stack value.

Initialize ret to 0 so the no-control-created path returns deterministic
success, while preserving the existing negative error return when
snd_ctl_add() fails.

Fixes: a67656f011d1 ("ALSA: usb-audio: qcom: Add USB offload route kcontrol")
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260605-alsa-usb-qcom-offload-ret-init-v1-1-dc72fcc4bd3b@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>