helper/command: strip replicated command name in log

helper/command: strip replicated command name in log

After commit 0840414f0e57 ("helper/command: do not replace new
commands with ocd_ prefix"), the command name is present in
argv[0], so there is no need to pass it directly. The current code
causes the command name to be logged twice, once explicitly and
then from the content of argv[0]:
	openocd -c 'debug_level 3; echo hello; shutdown'
	<snip>
	Debug: 13 3 command.c:142 script_debug(): command - echo echo hello
	<snip>
	Debug: 16 4 command.c:142 script_debug(): command - shutdown shutdown

Remove the command name from the arguments of the function
script_debug().

Change-Id: I57860774f450ff717ee71ef9dc07590549a84319
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5660
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Tested-by: jenkins