mediatek: cleanup Huasifei WH3000 / WH3000 Pro dts

mediatek: cleanup Huasifei WH3000 / WH3000 Pro dts

WH3000 / WH3000 Pro button:
- These routers has no switch button, it's a regular button
  `linux,input-type = <EV_SW>;` removed

WH3000 Pro NAND:
- Add spi-nand calibration
- Align image size with vendor U-Boot partition layout:
  `nmbm0:1024k(bl2),512k(u-boot-env),2048k(factory),2048k(fip),231936k(ubi)`
- Remove redundant options from firmware build recipe
- Remove redundant `spi_nand:` label from DTS

Signed-off-by: Fil Dunsky <filipp.dunsky@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23227
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>