can: pch_can: fix error passive level test

The test (((errc & PCH_REC) >> 8) > 127) would always be false because
the receive error counter ((errc & PCH_REC) >> 8) is at most 127, where
PCH_REC is defined as 0x7f00.  To test whether the receive error counter
has reached the error passive level, the RP bit (15) should be used.
Signed-off-by: NXi Wang <xi.wang@gmail.com>
Acked-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/pch_can.c

@@ -66,6 +66,7 @@
 #define PCH_IF_CREQ_BUSY	BIT(15)
 
 #define PCH_STATUS_INT		0x8000
+#define PCH_RP			0x00008000
 #define PCH_REC			0x00007f00
 #define PCH_TEC			0x000000ff
 
@@ -527,7 +528,7 @@ static void pch_can_error(struct net_device *ndev, u32 status)
 		priv->can.can_stats.error_passive++;
 		state = CAN_STATE_ERROR_PASSIVE;
 		cf->can_id |= CAN_ERR_CRTL;
-		if (((errc & PCH_REC) >> 8) > 127)
+		if (errc & PCH_RP)
 			cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
 		if ((errc & PCH_TEC) > 127)
 			cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;