media: ov7670: restore default settings after power-up

Since commit 3d6a8fe2 ("media: ov7670: hook s_power onto v4l2 core"),
the device is actually powered off while the video stream is stopped.

The frame format and framerate are restored right after power-up, but
restoring the default register settings is forgotten.

Fixes: 3d6a8fe2 ("media: ov7670: hook s_power onto v4l2 core")

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Lubomir Rintel <lkundrak@v3.sk>
Tested-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>