wifi: rt2x00: remove unused delayed work data from link description

Remove unused 'agc_work' and 'vco_work' members of 'struct link'.
This follows commit d9632470 ("rt2x00: merge agc and vco works
with link tuner") where AGC and VCO calibration code was completely
redesigned. Compile tested only.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240515152824.143537-1-dmantipov@yandex.ru