media: coda: store device pointer in driver structure instead of pdev

Currently the platform device pointer is stored in struct coda_dev,
only to convert it into a device pointer wherever it is used. Just
store the device pointer directly.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>