Revert "[PATCH] generic_file_buffered_write(): handle zero-length iovec segments"

This reverts commit 81b0c871, which was
a bugfix against 6527c2bd

 ("[PATCH]
generic_file_buffered_write(): deadlock on vectored write"), which we
also revert.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>