V4L/DVB: saa7134: get rid of I2C_HW_SAA7134

The only reason for keeping I2C_HW_SAA7134 is to allow setting a
per-device polling interval. Just move this info to the platform
data, allowing drivers to change it per device, where needed.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>