i965_drv_driver: fix assertion failure
i965_drv_driver: fix assertion failure

CyanogenMod/android_hardware_intel_libva,halleyzhao/libva-fdo,01org/iotg-lin-gfx-libva,chenxianqin/vaapi-libva,01org/libva-cros,CyanogenMod/android_hardware_intel_libva,01org/iotg-lin-gfx-libva,halleyzhao/libva-fdo,CyanogenMod/android_hardware_intel_libva,android-ia/hardware_intel_libva,android-ia/hardware_intel_libva,chenxianqin/vaapi-libva,Distrotech/libva,zzhhui/libva,halleyzhao/libva-fdo,zzhhui/libva,gbeauchesne/libva,gbeauchesne/libva,android-ia/hardware_intel_libva,01org/libva-cros,gbeauchesne/libva,zzhhui/libva,Distrotech/libva,pma1/libva,chenxianqin/vaapi-libva,Distrotech/libva,01org/iotg-lin-gfx-libva,pma1/libva,01org/libva-cros,pma1/libva