[media] dvb-frontends/cxd2841er: define symbol_rate_min/max in T/C fe-ops

Fixes "w_scan -f c" complaining with

  This dvb driver is *buggy*: the symbol rate limits are undefined - please
  report to linuxtv.org)

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Acked-by: Abylay Ospan <aospan@netup.ru>
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>