ARM: orion: add ATAGS dependencies

ARM: orion: add ATAGS dependencies

Most of the remaining arm board files in the kernel are unused and will be
removed in early 2023 if no users step up.  So far I got no user replies
about the orion5x and mv78xx0 machines, but these are still supported
in the default kernel of the Debian 'armel' (armv5 softfloat) distro,
and there is an active project on github that tries to keep some of
these machines working, and Mauri Sandberg is working on a DT conversion
for the D-Link DNS-323.

It appears the Debian-on-Buffalo project has not got the Terastation WXL
working in a few years, and the other mv78xx0 machines are just the
reference designs, so I assume none of these have remaining users.

For the Orion5x family, the same is probably true for its reference
implementations (RD88Fxxxxx, DB88F281) and the machines with less than
64MB of memory (WNR854T, WRT350N v2).

The remaining nine machines are now scheduled to be kept for at least
2023, hopefully to be replaced with DT based versions.

The mv78xx0_defconfig file needs to enable CONFIG_UNUSED_BOARD_FILES
to still build, while the other affected defconfig files lose the
specific boards.

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: Mauri Sandberg <maukka@ext.kapsi.fi>
Link: https://github.com/1000001101000/Debian_on_Buffalo
Signed-off-by: Arnd Bergmann <arnd@arndb.de>