[media] fix clock_gettime cross-references

Fix those warnings:

	Documentation/media/uapi/cec/cec-ioc-dqevent.rst:124: WARNING: c:func reference target not found: clock_gettime(2)

By replacing it with the right function name, using this shell script:

	for i in `find Documentation/media -type f`; do sed 's,clock_gettime(2),clock_gettime,' <$i >a && mv a $i; done

Please notice that this will make the nitpick mode to shut up
complaining about that, becasue clock_gettime is on its exclude list,
but the cross reference will be undefined until someone documents
this function at the core documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/cec/cec-ioc-dqevent.rst

@@ -122,7 +122,7 @@ it is guaranteed that the state did change in between the two events.
        -  :cspan:`1` Timestamp of the event in ns.
 
 	  The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
-	  the same clock from userspace use :c:func:`clock_gettime(2)`.
+	  the same clock from userspace use :c:func:`clock_gettime`.
 
     -  .. row 2
 

Documentation/media/uapi/cec/cec-ioc-receive.rst

@@ -95,7 +95,7 @@ result.
 
        -  Timestamp in ns of when the last byte of the message was transmitted.
 	  The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
-	  the same clock from userspace use :c:func:`clock_gettime(2)`.
+	  the same clock from userspace use :c:func:`clock_gettime`.
 
     -  .. row 2
 
@@ -105,7 +105,7 @@ result.
 
        -  Timestamp in ns of when the last byte of the message was received.
 	  The timestamp has been taken from the ``CLOCK_MONOTONIC`` clock. To access
-	  the same clock from userspace use :c:func:`clock_gettime(2)`.
+	  the same clock from userspace use :c:func:`clock_gettime`.
 
     -  .. row 3
 

Documentation/media/uapi/v4l/buffer.rst

@@ -712,7 +712,7 @@ Buffer Flags
 	  clock). Monotonic clock has been favoured in embedded systems
 	  whereas most of the drivers use the realtime clock. Either kinds
 	  of timestamps are available in user space via
-	  :c:func:`clock_gettime(2)` using clock IDs ``CLOCK_MONOTONIC``
+	  :c:func:`clock_gettime` using clock IDs ``CLOCK_MONOTONIC``
 	  and ``CLOCK_REALTIME``, respectively.
 
     -  .. _`V4L2-BUF-FLAG-TIMESTAMP-MONOTONIC`:
@@ -723,7 +723,7 @@ Buffer Flags
 
        -  The buffer timestamp has been taken from the ``CLOCK_MONOTONIC``
 	  clock. To access the same clock outside V4L2, use
-	  :c:func:`clock_gettime(2)`.
+	  :c:func:`clock_gettime`.
 
     -  .. _`V4L2-BUF-FLAG-TIMESTAMP-COPY`:
 

Documentation/media/uapi/v4l/vidioc-dqevent.rst

@@ -152,7 +152,7 @@ call.
        -
        -  Event timestamp. The timestamp has been taken from the
 	  ``CLOCK_MONOTONIC`` clock. To access the same clock outside V4L2,
-	  use :c:func:`clock_gettime(2)`.
+	  use :c:func:`clock_gettime`.
 
     -  .. row 12