[media] docs-rst: fix some broken struct references

The :c:type: references point to the structure name, and not to
struct foo.

Fixed via this shell script:

	for i in `find Documentation/media -type f`; do perl -ne 'if (s/\:c\:type\:\`struct\s*(\S+)\`/struct :c:type:`$1`/) { s/struct\s+struct/struct/;  s/(struct\s+\:c\:type\:\`\S+\`)\s+structure/$1/;  } print $_' <$i >a && mv a $i; done

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/cec/cec-func-poll.rst

@@ -49,7 +49,7 @@ events.
 
 On success :c:func:`poll()` returns the number of file descriptors
 that have been selected (that is, file descriptors for which the
-``revents`` field of the respective :c:type:`struct pollfd` structure
+``revents`` field of the respective struct :c:type:`pollfd`
 is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in
 the ``revents`` field if there are messages in the receive queue. If the
 transmit queue has room for new messages, the ``POLLOUT`` and