multimedia/libva: unbreak DRI2 for XRDP after 20aae48cbec2

https://github.com/intel/libva/commit/aeba58590726

Xwayland (uses DRI3) and Xorg (has DRM master) are not affected.

Inspired by: PkgSrc

(cherry picked from commit f863a42f48bb27b5c334f893ac855509d023df98)