doc-rst: linux_tv: Error codes should be const

All error codes should be const. Most are, but there are
lots of places where we forgot to add <constant> at the DocBook.

Fix those via this small script:
	for i in $(git grep -lE "\s+E[A-Z]+\b" Documentation/linux_tv/); do perl -ne 's,([^\`])\b(E[A-Z]+)\b,\1``\2``,g; print $_' <$i >a && mv a $i; done

As there are false positives, we needed to merge only the changes
that make sense, skipping the c blocks and skipping things like
EDID, EN, ETS that were also converted by the above code.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/Documentation/linux_tv/media/v4l/vidioc-g-dv-timings.rst b/Documentation/linux_tv/media/v4l/vidioc-g-dv-timings.rst
index c9de292..2b2e154 100644
--- a/Documentation/linux_tv/media/v4l/vidioc-g-dv-timings.rst
+++ b/Documentation/linux_tv/media/v4l/vidioc-g-dv-timings.rst
@@ -42,13 +42,13 @@
 :ref:`v4l2_dv_timings <v4l2-dv-timings>`. These ioctls take a
 pointer to the struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
 structure as argument. If the ioctl is not supported or the timing
-values are not correct, the driver returns EINVAL error code.
+values are not correct, the driver returns ``EINVAL`` error code.
 
 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
 the current input or output does not support DV timings (e.g. if
 :ref:`VIDIOC_ENUMINPUT` does not set the
-``V4L2_IN_CAP_DV_TIMINGS`` flag), then ENODATA error code is returned.
+``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
 
 
 Return Value