imx-gpu-viv: add Wayland backend option

imx-gpu-viv: add Wayland backend option

This package has been tested with Wayland back-end using weston-imx
repository on a i.MX6Q Nitrogen6x:
https://source.codeaurora.org/external/imx/weston-imx/
(tag rel_imx_4.9.51_8mq_ga to work with both i.MX6 and i.MX8MQ)

Weston was started as follows:
 # export XDG_RUNTIME_DIR=/tmp
 # weston --tty=1 --device=/dev/fb0

Finally the Vivante sample apps were started from weston-terminal:
 # cd /usr/share/examples/viv_samples/vdk/
 # ./tutorial7

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