ARM: imx_v6_v7_defconfig: Select CONFIG_TMPFS_POSIX_ACL

Andreas Müller reports:

"Fixes:

| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[220]: Failed to apply ACL on /dev/v4l-subdev0: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[224]: Failed to apply ACL on /dev/v4l-subdev1: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[215]: Failed to apply ACL on /dev/v4l-subdev10: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[228]: Failed to apply ACL on /dev/v4l-subdev2: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[232]: Failed to apply ACL on /dev/v4l-subdev5: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[217]: Failed to apply ACL on /dev/v4l-subdev11: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[214]: Failed to apply ACL on /dev/dri/card1: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[216]: Failed to apply ACL on /dev/v4l-subdev8: Operation not supported
| Sep 04 09:05:10 imx6qdl-variscite-som systemd-udevd[226]: Failed to apply ACL on /dev/v4l-subdev9: Operation not supported

and nasty follow-ups: Starting weston from sddm as unpriviledged user fails
with some hints on missing access rights."

Select the CONFIG_TMPFS_POSIX_ACL option to fix these issues.

Reported-by: Andreas Müller <schnitzeltony@gmail.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>