media: docs: make RC documents more compatible with Sphinx 3.1+

Sphinx 3.x broke support for the cdomain.py extension, as the
c domain code was rewritten. Due to that, the c tags need to
be re-written, in order to use the new c domain notation.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/rc/lirc-get-features.rst

@@ -1,4 +1,5 @@
 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: RC
 
 .. _lirc_get_features:
 
@@ -14,8 +15,9 @@ LIRC_GET_FEATURES - Get the underlying hardware device's features
 Synopsis
 ========
 
-.. c:function:: int ioctl( int fd, LIRC_GET_FEATURES, __u32 *features)
-    :name: LIRC_GET_FEATURES
+.. c:macro:: LIRC_GET_FEATURES
+
+``int ioctl(int fd, LIRC_GET_FEATURES, __u32 *features)``
 
 Arguments
 =========
@@ -26,11 +28,9 @@ Arguments
 ``features``
     Bitmask with the LIRC features.
 
-
 Description
 ===========
 
-
 Get the underlying hardware device's features. If a driver does not
 announce support of certain features, calling of the corresponding ioctls
 is undefined.
@@ -184,7 +184,6 @@ LIRC features
 
     Unused. Kept just to avoid breaking uAPI.
 
-
 Return Value
 ============