bus: stm32_firewall: fix off by one in stm32_firewall_get_firewall()

The "nb_firewall" variable is the number of elements in the firewall[]
array, which is allocated in stm32_firewall_populate_bus().  So change
this > comparison to >= to prevent an out of bound access.

Fixes: 5c9668cf ("firewall: introduce stm32_firewall framework")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

drivers/bus/stm32_firewall.c

@@ -53,7 +53,7 @@ int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *f
 			return err;
 		}
 
-		if (j > nb_firewall) {
+		if (j >= nb_firewall) {
 			pr_err("Too many firewall controllers");
 			of_node_put(provider);
 			return -EINVAL;