intel: add dependency on genxml generated files

Drivers using genxml will start compilation before generated files are
created, so add a dependency to it.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Cc: mesa-stable@lists.freedesktop.org
(cherry picked from commit 48e48b85)
Conflicts resolved by Dylan

Conflicts:
	src/gallium/drivers/iris/meson.build