nandwrite: remove `autoplace' features

nandwrite: remove `autoplace' features

The `autoplace' option was meant to force an MTD_OOB_AUTO layout while
writing to flash. This option has not been properly supported for a very
long time, as the necessary ioctl, MEMSETOOBSEL, has been removed.
Apparently nobody uses this option. Kill it.

Other code depends on the availability of the `old_oobinfo' data, so we
move some code within a block that handles autoplacement if it's
*already* enabled. This, however, is inconsistent and should be cleaned
up shortly.

Note: this option may be re-implemented in the near future with the
addition of a new ioctl that allows on-the-fly chaning of MTD OOB modes.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>