serial: serial_stm32: Rename status register flags

Uart status register is named USART_ISR on STM32F7, STM32H7
and STM32MP1 SoCs family, but USART_SR only on STM32F4 SoCs.

Use USART_ISR_ prefix instead of USART_SR_ .

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c
index e2eeade..216a803 100644
--- a/drivers/serial/serial_stm32.c
+++ b/drivers/serial/serial_stm32.c
@@ -45,10 +45,10 @@
 	fdt_addr_t base = plat->base;
 	u32 isr = readl(base + ISR_OFFSET(stm32f4));
 
-	if ((isr & USART_SR_FLAG_RXNE) == 0)
+	if ((isr & USART_ISR_FLAG_RXNE) == 0)
 		return -EAGAIN;
 
-	if (isr & USART_SR_FLAG_ORE) {
+	if (isr & USART_ISR_FLAG_ORE) {
 		if (!stm32f4)
 			setbits_le32(base + ICR_OFFSET, USART_ICR_OREF);
 		else
@@ -65,7 +65,7 @@
 	bool stm32f4 = plat->uart_info->stm32f4;
 	fdt_addr_t base = plat->base;
 
-	if ((readl(base + ISR_OFFSET(stm32f4)) & USART_SR_FLAG_TXE) == 0)
+	if ((readl(base + ISR_OFFSET(stm32f4)) & USART_ISR_FLAG_TXE) == 0)
 		return -EAGAIN;
 
 	writel(c, base + TDR_OFFSET(stm32f4));
@@ -81,10 +81,10 @@
 
 	if (input)
 		return readl(base + ISR_OFFSET(stm32f4)) &
-			USART_SR_FLAG_RXNE ? 1 : 0;
+			USART_ISR_FLAG_RXNE ? 1 : 0;
 	else
 		return readl(base + ISR_OFFSET(stm32f4)) &
-			USART_SR_FLAG_TXE ? 0 : 1;
+			USART_ISR_FLAG_TXE ? 0 : 1;
 }
 
 static int stm32_serial_probe(struct udevice *dev)
diff --git a/drivers/serial/serial_stm32.h b/drivers/serial/serial_stm32.h
index 42fb132..6ebec0a 100644
--- a/drivers/serial/serial_stm32.h
+++ b/drivers/serial/serial_stm32.h
@@ -60,9 +60,9 @@
 
 #define USART_CR3_OVRDIS		BIT(12)
 
-#define USART_SR_FLAG_ORE		BIT(3)
-#define USART_SR_FLAG_RXNE		BIT(5)
-#define USART_SR_FLAG_TXE		BIT(7)
+#define USART_ISR_FLAG_ORE		BIT(3)
+#define USART_ISR_FLAG_RXNE		BIT(5)
+#define USART_ISR_FLAG_TXE		BIT(7)
 
 #define USART_BRR_F_MASK		GENMASK(7, 0)
 #define USART_BRR_M_SHIFT		4