ALSA: usb-audio: Fix Audio Advantage Micro II SPDIF switch

ALSA: usb-audio: Fix Audio Advantage Micro II SPDIF switch

snd_microii_spdif_switch_put() returns 0 when the requested
vendor register value differs from the cached one.

This comparison was inverted by the resume-support conversion,
so real SPDIF switch toggles are ignored while no-op writes still
issue SET_CUR and report success.

Return early only when the requested value matches the cached one.

Fixes: 288673beae6c ("ALSA: usb-audio: Add resume support for MicroII SPDIF ctls")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260421-microii-spdif-switch-fix-v1-1-5c50dc28b88f@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>