helper/command: register all commands through register_commands()

helper/command: register all commands through register_commands()

The commands "ocd_find" and "capture" are registered directly
through the jim API, instead of the common way to describe them
in a struct command_registration that is then passed to the helper
register_commands().
This cause the two commands above to not have either "help" nor
"usage" string nor a properly identified "mode".

Since the following line registers the commands listed in struct
command_builtin_handlers, simply add the two commands above in the
same struct.

Change-Id: Id6ee11dac3b18364deeed65ee8e18ad80152750a
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5644
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>