[nrf fromlist] boards: nordic: nrf54h20: Add adc to supported features

Enable twister tests execution on nrf54h20dk/nrf54h20/cpuppr target.

Upstream PR #: 97165

Signed-off-by: Bartlomiej Buczek <[email protected]>

Author: nordic-babu

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuppr_0_9_0.yaml

@@ -11,6 +11,7 @@ sysbuild: true
 ram: 62
 flash: 62
 supported:
+  - adc
   - counter
   - gpio
   - i2c