MAINTAINERS: rectify entry for ARM/NUVOTON NPCM ARCHITECTURE

Commit 08e95044 ("dt-binding: clk: npcm845: Add binding for Nuvoton
NPCM8XX Clock") obviously adds nuvoton,npcm845-clk.h, but the file entry in
MAINTAINERS, added with commit 3670d2ec ("arm64: npcm: Add support for
Nuvoton NPCM8XX BMC SoC") then refers to nuvoton,npcm8xx-clock.h.

Hence, ./scripts/get_maintainer.pl --self-test=patterns complains about a
broken reference.

Repair this file reference in ARM/NUVOTON NPCM ARCHITECTURE.

Fixes: 3670d2ec

 ("arm64: npcm: Add support for Nuvoton NPCM8XX BMC SoC")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>