imx-gpu-viv: enable package for 64-bit i.MX processors

Basically enabling the package for aarch64. One difference with 32-bit
i.MX platforms resides in the fact that Wayland is the only back-end
supported. Therefore X11 and Framebuffer options are masked.

This was tested on i.MX8MQ Nitrogen8M platform (with weston-imx):
 # cd /usr/share/examples/viv_samples/vdk/
 # ./tutorial7

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
[Thomas: drop BR2_PACKAGE_FREESCALE_IMX_HAS_VIV_GPU_WAYLAND_ONLY and
use BR2_PACKAGE_FREESCALE_IMX_PLATFORM_IMX8M directly.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>