qemu-socket: Polish errors for connect() and listen() failure

connect() doesn't "connect to socket", it connects a socket to an
address and, if it's of type SOCK_STREAM, initiates a connection.
Scratch "to".

listen() does "set socket to listening mode", but it sounds awkward.
Change to "listen on socket".
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NGonglei <arei.gonglei@huawei.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

include/qapi/qmp/qerror.h

@@ -155,10 +155,10 @@ void qerror_report_err(Error *err);
     ERROR_CLASS_GENERIC_ERROR, "this feature or command is not currently supported"
 
 #define QERR_SOCKET_CONNECT_FAILED \
-    ERROR_CLASS_GENERIC_ERROR, "Failed to connect to socket"
+    ERROR_CLASS_GENERIC_ERROR, "Failed to connect socket"
 
 #define QERR_SOCKET_LISTEN_FAILED \
-    ERROR_CLASS_GENERIC_ERROR, "Failed to set socket to listening mode"
+    ERROR_CLASS_GENERIC_ERROR, "Failed to listen on socket"
 
 #define QERR_SOCKET_BIND_FAILED \
     ERROR_CLASS_GENERIC_ERROR, "Failed to bind socket"