Blackfin arch: remove zero-sized include/asm-blackfin/macros.h

 This file accidentally got truncated instead of deleted in commit df30b117.

Signed-off-by: Marco Roeland <marco.roeland@xs4all.nl>
Cc: Robert P. J. Day <rpjday@mindspring.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Cc: Alex Riesen <raa.lkml@gmail.com>
Cc: Robin Getz <robin.getz@analog.com>
Acked-by: Bryan Wu <bryan.wu@analog.com>