In case of incorrect syntax, return ERROR_COMMAND_SYNTAX_ERROR so
the command framework will print the usage string.
Change-Id: I348debc77f470551d54fa77b4da780a48ff539c0
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8802
Tested-by: jenkins