ARM: Assume maintainership of ARM reference designs

With this I assume maintainership of the Integrator, Versatile
and RealView ARM reference machines.

It's no big secret that I've been maintaining them for years,
but might as well make it official so I get the mails and
don't miss anything.

I have also included some drivers that are closely associated
with the ARM reference designs and yet orphaned in the
MAINTAINERS file. I can surely maintain them too, or route
the question to the right people so it doesn't fall on the
floor of upward to the subsystem maintainers who have too much
to do already as it is.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Turquette <mturquette@baylibre.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>