[media] cx24116: add config option to split firmware download

It is very rare I2C adapter hardware which can provide 32kB I2C write
as one write. Add .i2c_wr_max option to set desired max packet size.
Split transaction to smaller pieces according to that option.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Cc: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>