linux/imx8mq-mnt-reform2-hdmi.dts: append 'HDMI' to model name

See merge request !4

patches/gst-plugins-bad1.0: disable gst-plugins-bad-dashdemux-improve-initial-representation-selection because gst_mpd_client_setup_streaming is incomplete

Only build natively if there are either arch:all or arch:any packages to build for the host architecture

build.sh: always set SOURCE_DATE_EPOCH if unset or set but null -- default to lastest git commit timestamp or date +%s

set SOURCE_DATE_EPOCH based on last git commit and use it for d/changelog and embed it in the kernel version