V4L/DVB (7323): pvrusb2: set default video standard to NTSC for OnAir HDTV / Creator

The pvrusb2 driver normally picks up the default video standard from the
eeprom on Hauppauge devices, but the OnAir HDTV and OnAir Creator are not
Hauppauge devices, and do not store this information in any eeprom.

These devices support NTSC/ATSC, so we should use NTSC by default when in
analog mode.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>