ALSA: usb-audio: Drop unnecessary parentheses in mixer_quirks

Fix multiple 'CHECK: Unnecessary parentheses around ...' reports from
checkpatch.pl.

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-v1-5-1a821463b632@collabora.com