media: ti-vpe: cal: Operate on phy instances in cal_quickdump_regs()

The cal_quickdump_regs() dumps registers for the two CAMERARX instances.
Retrieve those instances from the cal_dev directly instead of going
through the contexts, and simplify the code by using a loop.

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>