MAINTAINERS: remove obsolete file entry in MIPS/LOONGSON1 ARCHITECTURE

Commit c4649611

 ("clk: loongson1: Remove the outdated driver") removes
all files matching the pattern drivers/*/*/*loongson1*, but misses to
adjust the file entry for MIPS/LOONGSON1 ARCHITECTURE in MAINTAINERS.

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

Remove this file entry in MIPS/LOONGSON1 ARCHITECTURE.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20230323121437.28239-1-lukas.bulwahn@gmail.com
Acked-by: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>