i2c: designware: ratelimit 'transfer when suspended' errors

There are two problems with dev_err() here. One: It is not ratelimited.
Two: We don't see which driver tried to transfer something with a
suspended adapter. Switch to dev_WARN_ONCE to fix both issues. Drawback
is that we don't see if multiple drivers are trying to transfer while
suspended. They need to be discovered one after the other now. This is
better than a high CPU load because a really broken driver might try to
resend endlessly.

Link: https://bugs.archlinux.org/task/62391
Fixes: 27515415 ("i2c: designware: Do not allow i2c_dw_xfer() calls while suspended")
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Reported-by: Nskidnik <skidnik@gmail.com>
Acked-by: NJarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Nskidnik <skidnik@gmail.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-designware-master.c

@@ -426,8 +426,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	pm_runtime_get_sync(dev->dev);
 
-	if (dev->suspended) {
-		dev_err(dev->dev, "Error %s call while suspended\n", __func__);
+	if (dev_WARN_ONCE(dev->dev, dev->suspended, "Transfer while suspended\n")) {
 		ret = -ESHUTDOWN;
 		goto done_nolock;
 	}