i3c: master: Initialize ret in i3c_i2c_notifier_call()

Set ret to -EINVAL if i3c_i2c_notifier_call() receives an invalid
action, resolving uninitialized warning.

Signed-off-by: Jorge Marques <jorge.marques@analog.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250622-i3c-master-ret-uninitialized-v1-1-aabb5625c932@analog.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: gastmaier

drivers/i3c/master.c

@@ -2467,6 +2467,8 @@ static int i3c_i2c_notifier_call(struct notifier_block *nb, unsigned long action
 	case BUS_NOTIFY_DEL_DEVICE:
 		ret = i3c_master_i2c_detach(adap, client);
 		break;
+	default:
+		ret = -EINVAL;
 	}
 	i3c_bus_maintenance_unlock(&master->bus);