mtd: nand: raw: Move CONFIG_SYS_NAND_USE_FLASH_BBT to Kconfig

mtd: nand: raw: Move CONFIG_SYS_NAND_USE_FLASH_BBT to Kconfig

Convert CONFIG_SYS_NAND_USE_FLASH_BBT to Kconfig, update defconfigs,
headers and whitelist.

Please note that this symbol already was used in Kconfig
(imply in CONFIG_NAND_ATMEL) which did not work, since this symbol was
not available in Kconfig. This changes now with this patch and all
boards with CONFIG_NAND_ATMEL will have BBT enabled. Which is what
I also need on my GARDENA AT91SAM based board.

Signed-off-by: Stefan Roese <[email protected]>
Cc: Eugen Hristev <[email protected]>
Cc: Miquel Raynal <[email protected]>
Cc: Gregory CLEMENT <[email protected]>
[trini: Rework such that the configs are unchanged to start with]
Signed-off-by: Tom Rini <[email protected]>