cmd_mtdparts: Move to common handling of FLASH devices via MTD layer

cmd_mtdparts: Move to common handling of FLASH devices via MTD layer

This patch removes all references to the direct CFI FLASH interface
(via flash_info[]). Now that all FLASH types currently handled in
mtdparts are available (if selected, see below) via the MTD infrastructure.
This is NOR, NAND and OneNAND right now. This can be achieved by defining
the following options:

CONFIG_MTD_DEVICE (for all FLASH types)

plus

CONFIG_FLASH_CFI_MTD (for NOR FLASH)

So we need to add those defines to the board config headers currently
using the mtdparts commands. This is done via another patch, so
we shouldn't break mtdparts compatibility.

One big advantage from this solution is that the cmd_mtdparts.c is
*much* cleaner now. Lot's of #ifdef's are removed and the code itself
is smaller. Additionally the newly added MDT concatenation feature
can new be used via the mtdparts infrastructure and therefor via
UBI etc.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Ladislav Michl <ladis@linux-mips.org>
Cc: Scott Wood <scottwood@freescale.com>