samples: boards: st: power_mgmt: fix compilation issue

Fix compilation issue in test overlay nucleo_wba55cg.overlay

Signed-off-by: Khaoula Bidani <[email protected]>

Author: kbidani

samples/boards/st/power_mgmt/wkup_pins/boards/nucleo_wba55cg.overlay

@@ -6,7 +6,7 @@
 
 / {
 	aliases {
-		wkup-src = &button_0;
+		wkup-src = &user_button_1;
 	};
 };