media: tuners: fc0013 Remove unused functions

fc0013_rc_cal_add() and fc0013_rc_cal_reset() were added in 2012's
commit e889adc9 ("[media] fc001x: tuner driver for FC0013")
but haven't been used.

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>