arm: imx9: Correct imx9_probe_mu prototype

Since the event callback imx9_probe_mu is re-defined, update
its prototype.

Signed-off-by: Ye Li <ye.li@nxp.com>
diff --git a/arch/arm/include/asm/arch-imx9/mu.h b/arch/arm/include/asm/arch-imx9/mu.h
index b860499..649b8a6 100644
--- a/arch/arm/include/asm/arch-imx9/mu.h
+++ b/arch/arm/include/asm/arch-imx9/mu.h
@@ -8,6 +8,6 @@
 
 #include <event.h>
 
-int imx9_probe_mu(void *ctx, struct event *event);
+int imx9_probe_mu(void);
 
 #endif