ramips: Fix Hongdian H7920 v40 pinctrl default state

ramips: Fix Hongdian H7920 v40 pinctrl default state

According to the MT7628 hardware datasheet:
- GPIO/4 was originally used for I2C, but is now used as the Modem Power.
- GPIO/5 was originally used for I2C, but is now used as the SIM card select. (n/a for this device)
- GPIO/6 was originally used for SPI CS1, but is now used as the Serial mode switch.
- GPIO/36 was originally used for PERST, but is now used as the GPS OE. (n/a for this device)
- GPIO/38 was originally used for WDT, but is now used as the Modem2 Power. (n/a for this device)
- GPIO/44 was used for WLED_AN, but is now controlled by `gpio-leds`.

Corrected pinctrl to ensure it works properly in the future.

Signed-off-by: Coia Prant <coiaprant@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/20256
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>