command: log the command only when it is executed

command: log the command only when it is executed

In case of multi-word commands, the command dispatcher is nested
called at each word during command name parsing.
The improper position of the call to script_debug() causes the
command line to be logged once at each parsed word.
In the example of command "cpu arm disassemble 0" the full command
is logged three times for "cpu", "arm" and "disassemble":

	Debug: 656617 61843 command.c:201 script_debug(): command - cpu arm disassemble 0
	Debug: 656618 61843 command.c:201 script_debug(): command - cpu arm disassemble 0
	Debug: 656619 61843 command.c:201 script_debug(): command - cpu arm disassemble 0

Call script_debug() only when the parsing is terminated and the
command handler is going to be executed.

Change-Id: Ide4cb01b3b38912e2e24b073c94a9560f92d30bb
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6436
Tested-by: jenkins
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>