In order:
Add reference to relevant section of USBTMC usb488 subclass specs.
Print debug output of capabilities only when it was retrieved successfully.
Clear return value on success, otherwise driver always reports failure.
Signed-off-by: NGergely Imreh <imrehg@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>