realtek: add NAND hardware description to RTL93xx

realtek: add NAND hardware description to RTL93xx

Include the NAND specs into the DTS. It is unclear which devices
really need it. Keep it disabled for now. As the SoC register area
is defined too small until now, increase the size to an appropriate
value.

If enabled one can see the following log messages (e.g. Linksys
LGS328C or LGS352C).

[    1.206600] spi-nand spi1.0: Macronix SPI NAND was found.
[    1.212795] spi-nand spi1.0: 128 MiB, block size: 128 KiB, page size: 2048, OOB size: 64
[    1.222217] 3 fixed-partitions partitions found on MTD device spi1.0
[    1.229466] OF: Bad cell count for /soc/spi@1a400/flash@0/partitions
[    1.236617] OF: Bad cell count for /soc/spi@1a400/flash@0/partitions
[    1.244164] Creating 3 MTD partitions on "spi1.0":
[    1.249620] 0x000000000000-0x000004000000 : "ubifs"
[    1.423593] 0x000004000000-0x000005e00000 : "firmware"
[    1.738268] mtdsplit_uimage: no uImage found in "firmware"
[    1.744577] 0x000005e00000-0x000007c00000 : "runtime2"

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19583
Signed-off-by: Robert Marko <robimarko@gmail.com>