mtd: spi-nor: add opcodes for octal Read/Write commands

- Add opcodes for octal I/O commands
  * Read  : 1-1-8 and 1-8-8 protocol
  * Write : 1-1-8 and 1-8-8 protocol
  * opcodes for 4-byte address mode command

- Entry of macros in _convert_3to4_xxx function

- Add flag SPI_NOR_OCTAL_READ specifying flash support octal read
  commands. This flag is required for flashes which didn't provides
  support for auto detection of Octal mode capabilities i.e. not
  seems to support newer JESD216C standard.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Yogesh Narayan Gaur <yogeshnarayan.gaur@nxp.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>