tty: serial: qcom_geni_serial: Return IRQ_NONE for spurious interrupts

Currently the driver returns IRQ_HANDLED when spurious interrupts happen.
This is misleading. Fix the behavior by returning IRQ_NONE for spurious
interrupts.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -633,7 +633,7 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
 	struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
 
 	if (uport->suspended)
-		return IRQ_HANDLED;
+		return IRQ_NONE;
 
 	spin_lock_irqsave(&uport->lock, flags);
 	m_irq_status = readl_relaxed(uport->membase + SE_GENI_M_IRQ_STATUS);