mtd: rawnand: prepare the removal of the ONFI parameter page

The NAND chip parameter page is statically allocated within the
nand_chip structure, which reserves a lot of space. Even not ONFI nor
JEDEC chips have it embedded. Also, only a few parameters are actually
read from the parameter page after the detection.

ONFI-related parameters that will be used outside from the
identification function are stored in a separate onfi_parameters
structure embedded in nand_parameters, this small structure that
already hold generic parameters.

For now, the onfi_parameters structure is allocated statically. However,
after some deep rework in the NAND framework, it will be possible to do
dynamic allocations from the NAND identification phase, and this
strcuture will then be dynamically allocated when needed.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>