Core changes:
* Prepare arrival of the SPI NAND subsystem by implementing a generic
  (interface-agnostic) layer to ease manipulation of NAND devices
* Move onenand code base to the drivers/mtd/nand/ dir
* Rework timing mode selection
* Provide a generic way for NAND chip drivers to flag a specific
  GET/SET FEATURE operation as supported/unsupported
* Stop embedding ONFI/JEDEC param page in nand_chip

Driver changes:
* Rework/cleanup of the mxc driver
* Various cleanups in the vf610 driver
* Migrate the fsmc and vf610 to ->exec_op()
* Get rid of the pxa driver (replaced by marvell_nand)
* Support ->setup_data_interface() in the GPMI driver
* Fix probe error path in several drivers
* Remove support for unused hw_syndrome mode in sunxi_nand
* Various minor improvements