package/weston-imx: remove deprecated package

package/weston-imx: remove deprecated package

- the package couldn't be selected with vivante backend anyway since
  the split
- the package couldn't be updated to newer versions as it would imply
  forking libdrm and wayland-protocols for it to build
- drawback of not using NXP weston is the lack of G2D support, let's
  have it as a known issue for Buildroot but use standard weston
  package

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>