MAINTAINERS: EXYNOS: remove board files

Commit ca914350 ("ARM: EXYNOS: Remove unused board files") removed
the files, remove the patterns too.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>