meson: lift driver-collection out into parent build-file

meson: lift driver-collection out into parent build-file

This way we can mark the dri_drivers and dri_link arrays as temporary,
as all knowledge about them are contained in a single build-file with
clearly visible limited life-span.

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Acked-by: Dylan Baker <dylan@pnwbakers.com>