imx-base.inc: add imx-boot as a dependency for mx8m machines
imx-boot is required to be provided as a dependency for mx8m machines in
order to provide a boot container, which WIC is expecting to include
into the final image.
Since the only dependency for WIC present in the layer now is targeting
mx8 machine and MACHINEOVERRIDES_EXTENDER_FILTER_OUT removes it when
use-mainline-bsp is set - it leaves no 'imx-boot' container in the path
of creating WIC file, and build for mx8m machines fails.
Append WKS_FILE_DEPENDS to include imx-boot for mx8m, as it is required
to be present regardless of the BSP flavor chosen.
Fixes: e2589ccb ("imx-base.inc: Avoid adding 'imx-boot' as dependency for all SoCs") Signed-off-by: Andrey Zhizhikin <andrey.z@gmail.com>
