ALSA: usb-audio: Simplify NULL comparison in mixer_quirks

[ Upstream commit f2d6d660e8fd5f4467e80743f82119201e67fa9c ]

Handle report from checkpatch.pl:

  CHECK: Comparison to NULL could be written "t->name"

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250526-dualsense-alsa-jack-v1-7-1a821463b632@collabora.com


Signed-off-by: Sasha Levin <sashal@kernel.org>