Add the support of wrapper the VA Buffer to the backend driver

Add the support of wrapper the VA Buffer to the backend driver

The obj_context is passed when calling vaCreateBuffer, which can be
used to check whether it belongs to the wrapped context. If one VA buffer
belongs to wrapped buffer, the callback function of backend driver will
be called for the corresponding VA buffer.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Sean V Kelley <seanvk@posteo.de>
(cherry picked from commit f75ddc58b16cb93e85e737792c431415288cafb1)