It's not used. Fix the following on alpha-eb66 as a side effect:

In file included from drivers/net/lp486e.c:75:
include/asm/io.h:20:1: warning: "SLOW_DOWN_IO" redefined
drivers/net/lp486e.c:59:1: warning: this is the location of the previous definition
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>