irqchip/stm32: Fix initial values

-After cold boot, imr default value depends on hardware configuration.
-After hot reboot the registers must be cleared to avoid residue.
Signed-off-by: NLudovic Barre <ludovic.barre@st.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-stm32-exti.c

@@ -258,7 +258,16 @@ __init stm32_exti_init(const struct stm32_exti_bank **stm32_exti_banks,
 		writel_relaxed(~0UL, base + stm32_bank->rtsr_ofst);
 		irqs_mask = readl_relaxed(base + stm32_bank->rtsr_ofst);
 		nr_exti = fls(readl_relaxed(base + stm32_bank->rtsr_ofst));
+
+		/*
+		 * This IP has no reset, so after hot reboot we should
+		 * clear registers to avoid residue
+		 */
+		writel_relaxed(0, base + stm32_bank->imr_ofst);
+		writel_relaxed(0, base + stm32_bank->emr_ofst);
 		writel_relaxed(0, base + stm32_bank->rtsr_ofst);
+		writel_relaxed(0, base + stm32_bank->ftsr_ofst);
+		writel_relaxed(~0UL, base + stm32_bank->pr_ofst);
 
 		pr_info("%s: bank%d, External IRQs available:%#x\n",
 			node->full_name, i, irqs_mask);