MAINTAINERS: s/SeongJae/SJ/

MAINTAINERS: s/SeongJae/SJ/

My legal and preferred first names are SeongJae and SJ, respectively.  I
was using the legal name for commits and tags, while using the preferred
name for conversations.  It sometimes confuses people including myself.
Consistently use the preferred name.

Together remove copyright notes on files.  Those are only confusing for
people who are not familiar with the law.  Meanwhile, we can infer the
information in a better way from git logs and public information.

Link: https://lore.kernel.org/20260630013820.143366-1-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Acked-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>