mtd: nand: Add manufacturer specific initialization/detection steps

A lot of NANDs are implementing generic features in a non-generic way,
or are providing advanced auto-detection logic where the NAND ID bytes
meaning changes with the NAND generation.

Providing this vendor specific initialization step will allow us to get
rid of full-id entries in the nand_ids table or all the vendor specific
cases added over the time in the generic NAND ID decoding logic.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>