machine: phyboard-mira-imx6-4: Update barebox image
machine: phyboard-mira-imx6-4: Update barebox image

The phyboard-mira-imx6-4 represents the phyCORE-i.MX 6Solo module with
256 MB RAM and NAND on a low-cost phyBOARD-Mira. This low-cost variant
is now represented by a different barebox image since both low-cost and
full-featured phyBOARD-Mira are now supported by this module.
So adapt the recipe to the new image.

The full-featured variant of this module is going to be represented by the
phyboard-mira-imx6-15 machine.

Signed-off-by: Stefan Riedmueller <c3365f3fb46321e09058054bbbd3cb5c9c2c30f7@phytec.de>
Signed-off-by: Wadim Egorov <f42ccee66aacafbe10be12a603629f53944208c9@phytec.de>

PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec