mtd: spi-nor: core: Introduce the late_init() hook

Flash parameters init is done in a spaghetti way right now.
There is the init based on the flash_info data, then there is the
default_init() hook, then SFDP init, an intermediary post_bft(),
then post_sfdp() and a spi_nor_late_init_params(). Each method can
overwrite previuosly initialized parameters.

We want to separate what is SFDP and non-SFDP specific. late_init()
will replace the default_init() hook and will be used only to initialize
flash parameters that are not declared in the JESD216 SFDP standard, or
where SFDP tables are not defined at all.
We cut a member in the chain of initializing parameters by getting rid
of the default_init() hook, and we make it clear that everything that is
in late_init() is not covered by the SFDP tables defined by the flash.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Link: https://lore.kernel.org/r/20211029172633.886453-6-tudor.ambarus@microchip.com