m73: New partition map for QSPI NOR flash

- Create two FSBL partitions, "boot" and "boot2"
- Create "bootenv" partition for U-boot environment
- Create "config" and "factory" partitions for future data storge
- Resize "image" partition
- Reserve top of flash for future
m55, m69, m72: Init script tweaks

- Add scan script which creates fstab entries for partitions on microSD and eMMC cards, or
  entire device if no partitions defined, for S35mountall.sh to auto-mount
- Add usb0 device to /etc/network/interfaces to autostart WiFi bridge if connected
m62: DTS entries for Ethernet

This is commented out by default, to avoid the DHCP client causing a boot delay for boards
without Ethernet hardware.  To enable, remove or comment out the line:
    status = "disabled";