MAINTAINERS: Mark the LatticeMico32 target as orphan

MAINTAINERS: Mark the LatticeMico32 target as orphan

Michael Walle expressed his desire to orphan the lm32 target [*]:

  I guess it is time to pull the plug. Mainly, because I have
  no time for this anymore. I've always worked on this on my
  spare time and life changed. And secondly, I guess RISC-V is
  taking over ;) It has a far better ecosystem. Also, to my
  knowledge the only (public) user of LM32 is milkymist and this
  project is dead for years now..

  So time to say goodbye. It was fun and I've learned a lot -
  technically and also how a huge open source project works.
  Thank you everyone for that :)

  Basically everything still works and there are even TCG test
  cases which covers all instructions the processor has.

Many thanks to Michael for his substantial contributions to QEMU,
and for maintaining the LM32 target for various years!

[*] https://www.mail-archive.com/[email protected]/msg605024.html

Acked-by: Michael Walle <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-Id: <20200316142827[email protected]>
Signed-off-by: Laurent Vivier <[email protected]>