MAINTAINERS: drop entry to removed file in ARM/RISCPC ARCHITECTURE

MAINTAINERS: drop entry to removed file in ARM/RISCPC ARCHITECTURE

Commit 009dac7c81d6 ("ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER") removes
arch/arm/include/asm/hardware/entry-macro-iomd.S, but missed to adjust
MAINTAINERS.

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

Drop the file entry to the removed file in ARM/RISCPC ARCHITECTURE.

Link: https://lkml.kernel.org/r/20220919075255.386-1-lukas.bulwahn@gmail.com
Fixes: 009dac7c81d6 ("ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>