ARM: 8096/1: Describe required sort order for textofs-y (TEXT_OFFSET)

The section of the makefile that determines the TEXT_OFFSET is sorted
by address so that, in multi-arch kernel builds, the architecture with the
most stringent requirements for the kernel base address gets to define
TEXT_OFFSET. The comment should reflect that.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>