media: ti-vpe: cal: Don't pass format to cal_ctx_wr_dma_config()

The cal_ctx_wr_dma_config() function has access to the context, there's
no need to give it format-related values retrieved from the context.
Access the values internally, and reword internal comments. The comment
regarding the CAL_WR_DMA_OFST register not being well understood is
dropped, as the datasheet explicitly documents it as "Offset between two
consecutive line starts".

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>