[U-Boot] [PATCH] arm: fix a comment

[Masahiro Yamada]

> Correct. While you're at it, can you also fix the comment on line 100:
> "r8 = gd->start_addr_sp" -> "sp = gd->start_addr_sp"

Thanks Benoit.
I modified my patch as suggested and posted it as v2.

Best regards,
Masahiro Yamada