Hauppauge EEPROM tuner code 168 has recently shown up on HVR-1600 TV
capture cards supported by the cx18 driver.  This change allows analog
tuner type autodetection to succeed for these cards.

Information for decoding tuner code 168 was provided by Hauppauge.
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>