[media] em28xx-input: remove dead code line from em28xx_get_key_em_haup()

Field 'old' of struct IR_i2c is used nowhere in module ir-kbd-i2c.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>