Allows to have other file system for boot partition without breaking
sysupgrade.

Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>

Add and enable sysupgrade support for clearfog boards, based on how the
brcm2708 target does it.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Acked-by: Felix Fietkau <nbd@nbd.name>

This way it's easier to configure device tree overlays, customize other
parameters...

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

SVN-Revision: 47126

Implement sysupgrade for Raspberry Pi, similar to the way it is done on x86:
The config files are saved in the boot partition and moved to where they are
normally expected in preinit.

Also add optional gzip compression for the SD card image, since this can save
a lot of space (76M vs 6M), also similar to x86.

Signed-off-by: Bruno Randolf <br1@einfach.org>

SVN-Revision: 46347