serial: sh-sci: Compute overrun_bit without using baud rate algo

The overrun bit index is a property of the hardware. It's currently
computed based on a different and unrelated hardware property, the baud
rate calculation algorithm. Compute it using hardware identification
information only.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

drivers/tty/serial/sh-sci.c

@@ -2133,30 +2133,38 @@ static int sci_init_single(struct platform_device *dev,
 			sci_port->irqs[i] = p->irqs[i] ? p->irqs[i] : -ENXIO;
 	}
 
+	if (p->regtype == SCIx_PROBE_REGTYPE) {
+		ret = sci_probe_regmap(p);
+		if (unlikely(ret))
+			return ret;
+	}
+
 	switch (p->type) {
 	case PORT_SCIFB:
 		port->fifosize = 256;
+		sci_port->overrun_bit = 9;
 		break;
 	case PORT_HSCIF:
 		port->fifosize = 128;
+		sci_port->overrun_bit = 0;
 		break;
 	case PORT_SCIFA:
 		port->fifosize = 64;
+		sci_port->overrun_bit = 9;
 		break;
 	case PORT_SCIF:
 		port->fifosize = 16;
+		if (p->regtype == SCIx_SH7705_SCIF_REGTYPE)
+			sci_port->overrun_bit = 9;
+		else
+			sci_port->overrun_bit = 0;
 		break;
 	default:
 		port->fifosize = 1;
+		sci_port->overrun_bit = 5;
 		break;
 	}
 
-	if (p->regtype == SCIx_PROBE_REGTYPE) {
-		ret = sci_probe_regmap(p);
-		if (unlikely(ret))
-			return ret;
-	}
-
 	if (!early) {
 		sci_port->iclk = clk_get(&dev->dev, "sci_ick");
 		if (IS_ERR(sci_port->iclk)) {
@@ -2194,12 +2202,6 @@ static int sci_init_single(struct platform_device *dev,
 	 * Establish sensible defaults for the overrun detection, unless
 	 * the part has explicitly disabled support for it.
 	 */
-	if (p->type == PORT_SCI)
-		sci_port->overrun_bit = 5;
-	else if (p->scbrr_algo_id == SCBRR_ALGO_4)
-		sci_port->overrun_bit = 9;
-	else
-		sci_port->overrun_bit = 0;
 
 	/*
 	 * Make the error mask inclusive of overrun detection, if