Support various flavors of chipselect:

 - EMIF chipselects, controlled by platform_device.id;
   now uses a spinlock for NANDFCR mutual exclusion.

 - NAND packages with multiple chipselects, with a new
   platform data field; use that for the dm355 EVM.

The EMIF CS support is only sanity tested; needs more, on a
board using NAND and HWECC on a nonzero chipselect.

Update the "no NAND chip" message so it doesn't presume a hack
specific to the dm6446evm:  "boot via NOR, then swap CS0 jumper";
and use the errno returned from nand_scan.

Plus minor tweaks:  rename 1-bit ECC procedures to match current
method names, not old 2.6.10 ones; and include marker comments
between driver sections.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>