V4L/DVB (6402): s5h1409: Fix broken QAM support

This patch enables QAM Annex-B support (US digital cable)
for the s5h1409 VSB/QAM demodulator.

Tested successfully with the mt2131 tuner,
present on the following supported boards:

Hauppauge WinTV-HVR-1250
Hauppauge WinTV-HVR-1800
Hauppauge WinTV-HVR-1800lp

This patch is also known to work with an upcoming XC5000 tuner driver.

Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>