Redirect hdparm + sg_inq errors to according .error files

Redirect hdparm + sg_inq errors to according .error files

sg_inq might raise:

Both SCSI INQUIRY and fetching ATA information failed on /dev/vda

and hdparm might raise:

HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
HDIO_GET_IDENTITY failed: Inappropriate ioctl for device

This is annoying when running grml-hwinfo under cron, so
let's redirect this output to their according .error files.