Conformance: vaQuerySurfaceAttributes does not adjust num_attribs

[uartie]

Per API documentation (https://github.com/01org/libva/blob/68a4befd03535bf9ed8077b27d8a0c421951a445/va/va.h#L1320):

 * The \c attrib_list array is allocated by the user and \c
 * num_attribs shall be initialized to the number of allocated
 * elements in that array. Upon successful return, the actual number
 * of attributes will be overwritten into \c num_attribs. Otherwise,
 * \c VA_STATUS_ERROR_MAX_NUM_EXCEEDED is returned and \c num_attribs
 * is adjusted to the number of elements that would be returned if
 * enough space was available.

iHD does not adjust num_attribs when VA_STATUS_ERROR_MAX_NUM_EXCEEDED and therefore client apps are unable to act accordingly.