[media] coda: allow more than four instances on CODA7541

With the new firmware, there are not anymore four register sets,
but a single register set, which the driver has to conserve across
context switches. This allows to handle more than four instances
at the same time.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>