rpmsg: char: Fix rpmsg_eptdev structure documentation

Add missing @ tags for some rpmsg_eptdev structure parameters.

This fixes warning messages on build:
drivers/rpmsg/rpmsg_char.c:75: warning: Function parameter or struct member 'remote_flow_restricted' not described in 'rpmsg_eptdev'
drivers/rpmsg/rpmsg_char.c:75: warning: Function parameter or struct member 'remote_flow_updated' not described in 'rpmsg_eptdev'

Fixes: 5550201c ("rpmsg: char: Add RPMSG GET/SET FLOWCONTROL IOCTL support")
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20240517165654.427746-1-arnaud.pouliquen@foss.st.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/rpmsg/rpmsg_char.c

@@ -52,8 +52,8 @@ static DEFINE_IDA(rpmsg_minor_ida);
  * @readq:	wait object for incoming queue
  * @default_ept: set to channel default endpoint if the default endpoint should be re-used
  *              on device open to prevent endpoint address update.
- * remote_flow_restricted: to indicate if the remote has requested for flow to be limited
- * remote_flow_updated: to indicate if the flow control has been requested
+ * @remote_flow_restricted: to indicate if the remote has requested for flow to be limited
+ * @remote_flow_updated: to indicate if the flow control has been requested
  */
 struct rpmsg_eptdev {
 	struct device dev;