MAINTAINERS: move Kyungmin Park to credits

MAINTAINERS: move Kyungmin Park to credits

Kyungmin Park maintained and contributed to some of the upstreamed
S5Pv210 and Exynos4210 machines - as described in commit 10ffa96407b2
("MAINTAINERS: add maintainer of Samsung Mobile Machine support").
However the entry in maintainers got slightly twisted by
commit 004bbd3c01d4 ("MAINTAINERS: remove non existent files") -
the directory matching pattern was changed from specific machines to
the entire S5Pv210.

Anyway since long time, all S5Pv210 maintenance is covered by the
Samsung ARM architectures maintainer entry and Krzysztof Kozlowski, so
move Kyungmin Park to the CREDITS.

There was also no activity on LKML regarding other maintained drivers:
https://lore.kernel.org/lkml/?q=f%3A%22Kyungmin+Park%22

Dear Kyungmin Park, thank you for all the effort you put in to the
upstream Samsung support.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Link: https://lore.kernel.org/r/20201016151528.7553-1-krzk@kernel.org