MIPS: kexec: fix typos

Correct a couple of typos within comments in
arch/mips/kernel/relocate_kernel.S.

[paul.burton@mips.com: Add a commit message.]

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Patchwork: https://patchwork.linux-mips.org/patch/19218/


Signed-off-by: Paul Burton <paul.burton@mips.com>