check-va-api fails on iHD driver: it does not implement VAProfileNone

The check-va-api helper assumes all VA-API drivers will implement the (VAProfileNone, VAEntrypointVideoProc) entry point, but Intel's iHD driver only implements:

libva info: VA-API version 1.9.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_8
libva info: va_openDriver() returns 0
vainfo: VA-API version: 1.9 (libva 2.8.0)
vainfo: Driver version: Intel iHD driver for Intel(R) Gen Graphics - 20.2.0 ()
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            :	VAEntrypointVLD
      VAProfileMPEG2Main              :	VAEntrypointVLD
      VAProfileH264Main               :	VAEntrypointVLD
      VAProfileH264Main               :	VAEntrypointEncSliceLP
      VAProfileH264High               :	VAEntrypointVLD
      VAProfileH264High               :	VAEntrypointEncSliceLP
      VAProfileJPEGBaseline           :	VAEntrypointVLD
      VAProfileJPEGBaseline           :	VAEntrypointEncPicture
      VAProfileH264ConstrainedBaseline:	VAEntrypointVLD
      VAProfileH264ConstrainedBaseline:	VAEntrypointEncSliceLP
      VAProfileVP8Version0_3          :	VAEntrypointVLD
      VAProfileHEVCMain               :	VAEntrypointVLD
      VAProfileHEVCMain10             :	VAEntrypointVLD
      VAProfileVP9Profile0            :	VAEntrypointVLD
      VAProfileVP9Profile2            :	VAEntrypointVLD

so this is not actually a useful check.

(What does Steam actually use VA-API for? We could diagnose problems more effectively if we knew which were the important entry points.)