ALSA: usb-audio: Add validation of UAC2/UAC3 effect units

Just add fixed struct size validations for UAC2 and UAC3 effect
units.  The descriptor has a variable-length array, so it should be
validated with a proper function later once when the unit is really
parsed and used by the driver (currently only referred partially for
the input terminal parsing).

Link: https://patch.msgid.link/20250821151751.12100-1-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>