pcm058: fix NAND flash not using badblock table

pcm058: fix NAND flash not using badblock table

Currently, U-Boot ignores the BBT stored in the last 4 blocks of NAND
flash because the NAND_BBT_USE_FLASH flag is not set.  This leads to
two issues:

* U-Boot silently uses a memory-only BBT which is initialized with all
  blocks marked as good.  This means, actual bad blocks are marked good
  and U-Boot might try writing to or reading from them.
* The BBT in flash, which will be created once Linux boots up, is not
  off limits for a driver ontop, like UBI.  While it does not seem to
  consistently produce an error, sometimes UBI will fail to attach
  because the BBT blocks obviously don't contain valid UBI data.

To fix this, this patch sets the CONFIG_SYS_NAND_USE_FLASH_BBT option,
which is used in ./drivers/mtd/nand/raw/mxs_nand.c to decide whether
a BBT in flash is used.

Signed-off-by: Harald Seiler <hws@denx.de>