Fix a da(4) driver memory leak for SCSI SMR devices.

In the probe case for SCSI SMR Host Aware or Most Managed drives, be sure
to free allocated memory.

sys/cam/scsi/scsi_da.c:
In dadone_probezone(), free the data pointer before returning.

MFC after: 3 days
Sponsored by: Spectra Logic
Approved by: re (kib)