linux-phytec-ti

MAINTAINERS: RISC-V Updates

This patch set contains a pair of RISC-V related updates to the
MAINTAINERS file:

* Albert is now back at UC Berkeley.
* I've added myself as a maintainer for anything with "sifive" in the
  name.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>