V4L/DVB (3300): Add standard for South Korean NTSC-M using A2 audio.

South Korea uses NTSC-M but with A2 audio instead of BTSC. Several audio
chips need this information in order to set the correct audio processing
registers.

Acked-by: Mauro Carvalho Chehab <mauro_chehab@yahoo.com.br>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>