microblaze: Fix ret_from_fork declaration

ret_from_fork is used by noMMU system too.

It should be the part of patch
"Disintegrate asm/system.h for Microblaze"
(sha1: c40d04df152a1111c5bbcb632278394dabd2b73d)

Signed-off-by: Michal Simek <monstr@monstr.eu>
1 file changed