filesetup: revert O_DIRECT for layout mess

filesetup: revert O_DIRECT for layout mess

This commit essentially reverts the following fives commits:

d33db728d ("fix regression by 8c43ba62('filesetup: align layout buffer')")
47534cda0 ("filesetup: add non O_DIRECT direct I/O support for initial layout setup")
6c3169f9c ("filesetup: add direct=1 failure warning to layout")
8c43ba625 ("filesetup: align layout buffer")
6e344dc34 ("filesetup: keep OS_O_DIRECT flag when pre-allocating file")

in reverse order, since we keep having issues with the basic idea of
using O_DIRECT for file layout or extensions, if the job file has
asked for O_DIRECT.

Signed-off-by: Jens Axboe <axboe@kernel.dk>