boundary: add new bootscript folder

Based on 6x_bootscript*.txt but using the variables name from
config_distro_bootcmd.h.

Also using $prefix as $bootdir for Yocto and Mainline versions.
boundary: bootscript: yocto: remove obsolete commands
boundary: bootscripts: fix bad disk variable replacement
boundary: bootscripts: net_upgradeu_fs: fix loaded script name
boundary: bootscripts: net_upgradeu_fs: update to match distro_bootcmd
boundary: bootscripts: add README file
boundary: bootscripts: rename folder to be plural
boundary: bootscripts: net_upgradeu_fs: remove active_partition

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>

boundary: bootscripts: add upgrade.txt
boundary: bootscripts: s/\${cpu}/\${imx_cpu}/g

cpu already has a standard definition. Move to imx_cpu
so that eventual we can also use the standard definition of cpu.

boundary: bootscripts: s/dtbname/fdt_file/g

Again fdt_file seems to be the standard for which dtb
file to load. Noone else uses dtbname.

boundary: bootscripts: remove references to ${bootdir}, or replace with ${prefix}
boundary: bootscripts: net_upgrade_fs=net_upgrade_fs.scr
boundary: bootscripts: prevent hdmi audio from being card 0
boundary: bootscripts: ubuntu: check for console environment var before adding to bootargs
boundary: bootscripts: upgrade: check for chip at45db041d so that erase is not too big for chip
boundary: bootscripts: net_upgradeu: check for chip at45db041d so that erase is not too big for chip

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>

boundary: honor distro_bootpart in u-boot upgrade

upgrade.txt hard codes all file accesses to partition 1 instead of
honoring the standard u-boot variable distro_bootpart.

Replace all occurrences of ${devnum}:1 with ${devnum}:${distro_bootpart}

Signed-off-by: Stefan Becker <sbecker@neolitics.com>