nrf5340 not powered in high voltage mode

[HFrg]

I was testing a custom board with an ISP2053. Everything was working as expected when powered in normal voltage mode directly with 3V0 on VCC. 

The device was not working when powered in high voltage mode.

I have found the problem as of posting. Leaving this here if it helps others.

[HFrg]

The problem was that `CONFIG_BOARD_ENABLE_DCDC_HV` defaults to `y` and the custom board did not have an inductor connected to DCCH. The ISP2053 has inductors for two out of the three DCDC converters.

Recompiling and flashing with:

```

CONFIG_BOARD_ENABLE_DCDC_APP=y

CONFIG_BOARD_ENABLE_DCDC_NET=y

CONFIG_BOARD_ENABLE_DCDC_HV=n

```

solved the problem.