It should be V4L2_TUNER_MODE_LANG1_LANG2. What the code does is check if 
we are NTSC and a SAP channel is available. If so, then the msp3400 
should switch to standard 0x21 if the user wants to hear the SAP 
channel, which is for audio modes LANG2 (aka SAP) and LANG1_LANG2 
(bilingual).

In the msp3400 driver STEREO is abused for bilingual in PAL. Bilingual 
never worked with NTSC in the past and I decided that I'd better not 
use the bad PAL example.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>