powerpc: Update wiki link in MAINTAINERS

The wiki has moved, update the link.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200224233146.23734-2-mpe@ellerman.id.au
This commit is contained in:
Michael Ellerman 2020-02-25 10:31:40 +11:00
commit fd65a1aaad