pch_uart: Fix return value issue

Currently, occurring line status interrupt,
returned value is not set in interrupt handler function.
As a result, 0 can be returned.

This patch adds setting returned value.
Signed-off-by: NTomoya MORINAGA <tomoya.rohm@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/pch_uart.c

@@ -39,6 +39,7 @@ enum {
 	PCH_UART_HANDLED_RX_ERR_INT_SHIFT,
 	PCH_UART_HANDLED_RX_TRG_INT_SHIFT,
 	PCH_UART_HANDLED_MS_INT_SHIFT,
+	PCH_UART_HANDLED_LS_INT_SHIFT,
 };
 
 enum {
@@ -63,6 +64,8 @@ enum {
 					PCH_UART_HANDLED_RX_TRG_INT_SHIFT)<<1))
 #define PCH_UART_HANDLED_MS_INT	(1<<((PCH_UART_HANDLED_MS_INT_SHIFT)<<1))
 
+#define PCH_UART_HANDLED_LS_INT	(1<<((PCH_UART_HANDLED_LS_INT_SHIFT)<<1))
+
 #define PCH_UART_RBR		0x00
 #define PCH_UART_THR		0x00
 
@@ -1058,6 +1061,8 @@ static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
 						UART_LSR_PE | UART_LSR_OE)) {
 				pch_uart_err_ir(priv, lsr);
 				ret = PCH_UART_HANDLED_RX_ERR_INT;
+			} else {
+				ret = PCH_UART_HANDLED_LS_INT;
 			}
 			break;
 		case PCH_UART_IID_RDR:	/* Received Data Ready */