ide-tape: fix vendor strings

Remove superfluous two bytes from each string buffer and add proper length
format specifiers.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Tested-by: Mark de Wever <koraq@xs4all.nl>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>