Revert "[media] dvb_frontend: return -ENOTTY for unimplement IOCTL"

As reported by Klaus Schmidinger:
 "In VDR I use an ioctl() call with FE_READ_UNCORRECTED_BLOCKS on a
  device (using stb0899).  After this call I check 'errno' for
  EOPNOTSUPP to determine whether this device supports this call.  This
  used to work just fine, until a few months ago I noticed that my
  devices using stb0899 didn't display their signal quality in VDR's OSD
  any more.  After further investigation I found that
  ioctl(FE_READ_UNCORRECTED_BLOCKS) no longer returns EOPNOTSUPP, but
  rather ENOTTY.  And since I stop getting the signal quality in case
  any unknown errno value appears, this broke my signal quality query
  function."

While the changes reflect what is there at:

  http://comments.gmane.org/gmane.linux.kernel/1235728

it does cause regression on userspace.  So, revert it to stop the
damage.

This reverts commit 177ffe50 ("[media] dvb_frontend: return -ENOTTY
for unimplement IOCTL").
Reported-by: Klaus Schmidinger <Klaus.Schmidinger@tvdr.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/media/dvb-core/dvb_frontend.c

@@ -1820,7 +1820,7 @@ static int dvb_frontend_ioctl(struct file *file,
 	struct dvb_frontend *fe = dvbdev->priv;
 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
-	int err = -ENOTTY;
+	int err = -EOPNOTSUPP;
 
 	dev_dbg(fe->dvb->device, "%s: (%d)\n", __func__, _IOC_NR(cmd));
 	if (fepriv->exit != DVB_FE_NO_EXIT)
@@ -1938,7 +1938,7 @@ static int dvb_frontend_ioctl_properties(struct file *file,
 		}
 
 	} else
-		err = -ENOTTY;
+		err = -EOPNOTSUPP;
 
 out:
 	kfree(tvp);
@@ -2071,7 +2071,7 @@ static int dvb_frontend_ioctl_legacy(struct file *file,
 	struct dvb_frontend *fe = dvbdev->priv;
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
-	int err = -ENOTTY;
+	int err = -EOPNOTSUPP;
 
 	switch (cmd) {
 	case FE_GET_INFO: {