Fix incorrect std::string object usage

Modifed the code to pass string data pointer
instead of the string object reference

Tested:
user password were tested with IPMI
commands and no crash were observed

Signed-off-by: gokulsanker <gokul.sanker.v.g@intel.com>
Change-Id: I12d96965cd8c91d6aa1d925ac55b22f31d08d2fe
diff --git a/user_channel/usercommands.cpp b/user_channel/usercommands.cpp
index 9a23ac3..2ef6b87 100644
--- a/user_channel/usercommands.cpp
+++ b/user_channel/usercommands.cpp
@@ -419,15 +419,15 @@
             log<level::DEBUG>("Test password failed",
                               entry("USER-ID=%d", (uint8_t)req->userId));
             // Clear sensitive data
-            OPENSSL_cleanse(&testPassword, testPassword.length());
-            OPENSSL_cleanse(&password, password.length());
+            OPENSSL_cleanse(testPassword.data(), testPassword.length());
+            OPENSSL_cleanse(password.data(), password.length());
 
             return static_cast<Cc>(
                 IPMISetPasswordReturnCodes::ipmiCCPasswdFailMismatch);
         }
         // Clear sensitive data
-        OPENSSL_cleanse(&testPassword, testPassword.length());
-        OPENSSL_cleanse(&password, password.length());
+        OPENSSL_cleanse(testPassword.data(), testPassword.length());
+        OPENSSL_cleanse(password.data(), password.length());
 
         return ccSuccess;
     }