user_channel:Remove unused ipmiUserSetUserName API

ipmiUserSetUserName API signature is changed to use string variable.
So removed unused API

Tested:
Verified using ipmitool commands.
Command: ipmitool user set name 4 user4
Response:    //Success
Command: ipmitool user set password 4 asdf1234
Response: Set User Password command successful (user 4)
Command: ipmitool user priv 4 0x03 1
Response: Set Privilege Level command successful (user 4)
Command: ipmitool user set name 14 user13asdfghkjlqwert
Response: Username is too long (> 16 bytes)
Command: ipmitool -I lanplus -C 17 -p 623 -U root -P <password> -H
         <BMC-IP> user set name 8 WIJGueNKd
Response:                       //Success
Command: ipmitool user list 1 //User list for channel 1
Response:
ID  Name             Callin  Link Auth  IPMI Msg   Channel Priv Limit
1   root             false   true       true       ADMINISTRATOR
2                    true    false      false      NO ACCESS
3                    true    false      false      NO ACCESS
4   user4            true    false      false      OPERATOR
5   WIJGueNKda       true    false      false      NO ACCESS
6                    true    false      false      NO ACCESS
7                    true    false      false      NO ACCESS
8   WIJGueNKd        true    false      false      NO ACCESS
9                    true    false      false      NO ACCESS

Signed-off-by: jayaprakash Mutyala <mutyalax.jayaprakash@intel.com>
Change-Id: I6ae8349f61fc658d4e74d923711325eae6f8088a
diff --git a/user_channel/user_layer.hpp b/user_channel/user_layer.hpp
index 0639474..01b6634 100644
--- a/user_channel/user_layer.hpp
+++ b/user_channel/user_layer.hpp
@@ -135,13 +135,10 @@
 uint8_t ipmiUserGetUserId(const std::string& userName);
 
 /** @brief set's user name
- *
- *  @param[in] userId - user id
- *  @param[in] userName - user name
- *
- *  @return ccSuccess for success, others for failure.
+ *  This API is deprecated
  */
-Cc ipmiUserSetUserName(const uint8_t userId, const char* userName);
+Cc ipmiUserSetUserName(const uint8_t userId, const char* userName)
+    __attribute__((deprecated));
 
 /** @brief set's user name
  *