boards: nordic: nrf54h20dk: Add SPI to supported features on PPR XIP

Enable Twister tests that depend on SPI feature
on nrf54h20dk/nrf54h20/cpuppr/xip target.

Signed-off-by: Sebastian Głąb <[email protected]>

Author: nordic-segl

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuppr_xip_0_9_0.yaml

@@ -12,3 +12,4 @@ ram: 62
 flash: 64
 supported:
   - gpio
+  - spi