nand: atmel: Add DM based NAND driver

This implementation is ported from the rework done by Boris Brezillon
in Linux. This porting is done based on linux-5.4-at91. The driver is
tested in sam9x60ek, sama5d3_xplained, sam9x75eb and sama7g54-ddr3-eb.

Changes done includes

- Adapt GPIO descriptor apis for U-Boot. Use gpio_request_by_name_nodev,
  dm_gpio_get_value etc.
- Use U_BOOT_DRIVER instead of platform_driver.
- Replace struct platform_device with struct udevice
- Check the status of nfc exec operation by polling the status
  register instead of interrupt based handling
- DMA operations not supported. Remove it
- Adapt DT parsing to U-Boot APIs

Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@microchip.com>