[PATCH] Correct sa'K' description in sysrq.txt

sysrq SAK is described as being something you should mistake for SAK from
c2 compliant systems - whoops.  What's meant is that it should *not* be
mistaken as such.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>