MAINTAINERS: MIPS/LOONGSON2 ARCHITECTURE - Use the normal wildcard style

Neither git nor get_maintainer understands the curly brace style.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20821/
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips <linux-mips@linux-mips.org>
Cc: LKML <linux-kernel@vger.kernel.org>