Command function
----------------
-The commmand function pointer has to be of type
+The command function pointer has to be of type
int (*cmd)(struct cmd_tbl_s *cmdtp, int flag, int argc, const char *argv[]);
cmdtp: Table entry describing the command (see above).
Allowable return value are:
-CMD_SUCCESS The command was successfully executed.
+CMD_RET_SUCCESS The command was successfully executed.
-CMD_FAILURE The command failed.
+CMD_RET_FAILURE The command failed.
CMD_RET_USAGE The command was called with invalid parameters. This value
leads to the display of the usage string.