alpha: lib: export __delay

__delay was not exported as a result while building with allmodconfig we
were getting build error of undefined symbol.  __delay is being used by:
drivers/net/phy/mdio-octeon.c

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>