Zephyr: MEMFAULT_METRICS_CPU_TEMP incorrectly enabled

[JordanYates]

MEMFAULT_METRICS_CPU_TEMP is incorrectly enabled when there is no die-temp0 alias, as the depends on should not be checking against "".

memfault-firmware-sdk/ports/zephyr/Kconfig

Line 503 in 0bd360f

depends on ADC && SENSOR && ("$(dt_alias_enabled,die-temp0)" != "")

The implementation of dt_alias_enabled returns either "y" or "n", which will never equal "".
https://github.com/zephyrproject-rtos/zephyr/blob/3f6d78c26c6fa1126eda7de51183bcf055afe9e7/scripts/kconfig/kconfigfunctions.py#L149

Additionally, there is no reason that ADC should be part of the dependencies, it is possible to read the internal die temperature without an ADC being enabled (see nRF modem AT%XTEMP)

The proper check should be:

 depends on SENSOR && "$(dt_alias_enabled,die-temp0)" 

[noahp]

Thanks @JordanYates ! I'll pull this into our next SDK release (scheduled for sometime this week), I'll update here when it's published.