[media] SoC Camera: add support for g_parm / s_parm operations

This patch adds support for g_parm / s_parm operations to the SoC Camera
framework. It is usefull for checking/setting camera frame rate.

Example usage can be found in the previous patch from this series,
"SoC Camera: add driver for OV6650 sensor".

Created and tested against linux-2.6.36-rc3 on Amstrad Delta.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>