spi: Introduce setup_for_spinand()

spi: Introduce setup_for_spinand()

A common device attached to SPI are SPI NAND and some device might
require to have info on the attached NAND to know the flash page size
and spare size.

To support this, introduce setup_for_spinand() that pass the attached
spinand info from manufacturer.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
[trini: Switch to forward declaration of struct spinand_info]
Signed-off-by: Tom Rini <trini@konsulko.com>