MIPS: Cleanup the Makefile of compressed kernel support

This patch removes a useless "\" (line break) and tunes the format of a
long line.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/869/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>