help: fix line size in 'usage' output
The implementation of command 'usage' is broken while checking the
line limit of 76 chars per line (e.g. 'usage load_image') and the
line wrapping is not correct. The same broken code is used for the
first output line of command 'help' too.
When call command_help_show_wrap(), include the command's name in
the string so the whole text would be wrapped.
Change-Id: Idece01ce54994db7e851d8522435ff764b11f3ac
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6223
Tested-by: jenkins