[Backport ncs-v3.1-branch] [nrf fromlist] boards: nordic: nrf54h20dk: Disable EXMIF and GPIO6 by default

External flash memory is typically not used, so it should
be disabled by default. The GPIO6 port used by this device
should also be disabled.

Upstream PR #: 94180

Signed-off-by: Adam Kondraciuk <[email protected]>

Author: adamkondraciuk

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp.dts

@@ -264,14 +264,14 @@ slot3_partition: &cpurad_slot1_partition {
 };
 
 &gpio6 {
-	status = "okay";
+	status = "disabled";
 };
 
 &exmif {
 	pinctrl-0 = <&exmif_default>;
 	pinctrl-1 = <&exmif_sleep>;
 	pinctrl-names = "default", "sleep";
-	status = "okay";
+	status = "disabled";
 
 	mx25uw63: mx25uw6345g@0 {
 		compatible = "mxicy,mx25u", "jedec,mspi-nor";