media: ipu3-cio2: rename cio2 bridge to ipu bridge and move out of ipu3

cio2 bridge was involved along with IPU3. However, in fact all Intel IPUs
besides IPU3 CIO2 need this bridge driver. This patch move bridge driver
out of ipu3 directory and rename as ipu-bridge. Then it can be worked with
IPU3 and other Intel IPUs.

Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>