Revert "netfs: Fix unbuffered write error handling"

This reverts commit f08c80af which is
commit a3de58b1 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ie73e5c28c1618a4ee498a41136ef7ab34b61580b
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>