[media] coda: fix FMO value setting for CodaDx6

The register is only written on CodaDx6, so the temporary variable
to be written only needs to be initialized on CodaDx6. Also, drop
two no-op lines.

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>