lib: cpu: Check return value from platform_boot_complete

Add error handling for platform_boot_complete() during D3 exit to
improve debugging capabilities.

Previously, platform_boot_complete() could fail silently if the DSP
entered D3 state with an invalid IPC driver state, making it difficult
to identify the root cause of issues. This change captures the return
value and triggers a panic with a clear error message when the function
fails.

This improvement makes debugging easier by explicitly indicating when
the boot completion fails after resuming from D3, rather than allowing
execution to continue with potential undefined behavior.

Signed-off-by: Tomasz Leman <tomasz.m.leman@intel.com>

Author: tmleman

zephyr/lib/cpu.c

@@ -211,7 +211,12 @@ void cpu_notify_state_exit(enum pm_state state)
 		global_imr_ram_storage = NULL;
 
 		/* send FW Ready message */
-		platform_boot_complete(0);
+		int ret = platform_boot_complete(0);
+
+		if (ret) {
+			tr_err(&zephyr_tr, "platform_boot_complete failed: %d", ret);
+			k_panic();
+		}
 #endif
 	}
 }