MAINTAINERS: add Patrick Williams
MAINTAINERS: add Patrick Williams

Large portions of the codebase were originally written by me
before maintainers existed.  I am returning to the project and
plan to do significant enhancements and cleanups to sdbusplus.

Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>
Change-Id: I3ac6f6597c78041785ded272d1e6ce8974d5b49a

openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus