copy_data currently loops over bio's in a list, but the caller also does the
same looping, sometimes with extra work.  So remove the loop from copy_data.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>