ARM: 8290/1: decompressor: fix a wrong comment

This comment does not correspond to the actual code.

When zImage is loaded at a lower *OR* higher address of
the destination of Image, it won't overwrite itself.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>