config: fix vaCreateConfig() to not override user chroma format.
config: fix vaCreateConfig() to not override user chroma format.

Only validate the user-defined chroma format (VAConfigAttribRTFormat)
attribute, if any. Don't override it. i.e. append a pre-defined value
only if it was not defined by the user beforehand.

Propertly return VA_STATUS_ERROR_UNSUPPORTED_RT_FORMAT if the supplied
chroma format is not supported.

Signed-off-by: Gwenole Beauchesne <729713629d9640cc095f1c77c692e1881f8093c4@intel.com>

01org/iotg-lin-gfx-va-driver,uartie/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,gbeauchesne/libva-intel-driver,uartie/vaapi-intel-driver,uartie/vaapi-intel-driver,uartie/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,gbeauchesne/libva-intel-driver,chenxianqin/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,gbeauchesne/libva-intel-driver,gbeauchesne/libva-intel-driver,01org/iotg-lin-gfx-va-driver,uartie/vaapi-intel-driver,01org/iotg-lin-gfx-va-driver,gbeauchesne/libva-intel-driver