mtd: spinand: winbond: W35N octal DTR support

mtd: spinand: winbond: W35N octal DTR support

Extend the support for the W35N chip family by supporting the ODTR bus
interface. The chip is capable to run in this mode, which brings a
significant performance improvement.

1S-8S-8S:

   # flash_speed /dev/mtd0 -c1 -d
   eraseblock write speed is 7529 KiB/s
   eraseblock read speed is 15058 KiB/s

8D-8D-8D:

   # flash_speed /dev/mtd0 -c1 -d
   eraseblock write speed is 9481 KiB/s
   eraseblock read speed is 23272 KiB/s

This is +55% read speed and +26% write speed with the same hardware.

Tests have been conducted with a TI AM62A7 using the Cadence quad SPI
controller.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>