jtag/aice: fix command's usage string

The usage string should contain only the command parameters.
OpenOCD will automatically prepend the command name to the usage
string while dumping the usage or help message.

Remove the repeated command name from the usage string.

Change-Id: Idbc301b34fab19e221131d232577c1629568e6ea
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5823
Tested-by: jenkins
1 file changed