fs/affs/symlink.c: remove unneeded err variable

err is only assigned to -EIO.  Return that value at the end of fail
context.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>