package/mpv: disable vaapi with DRI driver

package/mpv: disable vaapi with DRI driver

Build of vaapi with BR2_PACKAGE_MESA3D_DRI_DRIVER is broken since commit
17a7abbafee9bf4a971e00da7870ae439910e47e because vaapi can only be
enabled with x11, wayland or egl-drm
(https://github.com/mpv-player/mpv/blob/ec0006bfa1aaf608a7141929f2871c89ac7a15d6/wscript#L632):

'deps': 'libdl && (x11 || wayland || egl-drm)',

As a result, despite what is being displayed in the autobuilder log
message, the build failure is not related to X11 but to the fact that
we try to enable vaapi through a DRI driver but without egl.

Fixes:
 - http://autobuild.buildroot.org/results/5ae706e94eb6e5a3aa69368f81c5d12e608b1a5a

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>