spi/rockchip: Don't warn if SPI is busy but disabled

The reference manual from Rockchip claims this about the BSF (SPI Busy
Flag):
* 0 - SPI is idle or disabled
* 1 - SPI is actively transferring data

The above doesn't quite appear to be true.  Specifically I found the
busy bit set when SPI was disabled.  Let's change the WARN_ON() so we
only check the busy bit if the controller was enabled.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-rockchip.c

@@ -529,7 +529,8 @@ static int rockchip_spi_transfer_one(
 	int ret = 0;
 	struct rockchip_spi *rs = spi_master_get_devdata(master);
 
-	WARN_ON((readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));
+	WARN_ON(readl_relaxed(rs->regs + ROCKCHIP_SPI_SSIENR) &&
+		(readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));
 
 	if (!xfer->tx_buf && !xfer->rx_buf) {
 		dev_err(rs->dev, "No buffer for transfer\n");