[SCSI] sym2: claim only "Storage" class

The follow patch fixes a problem for Matt Taggart.
The Compaq system he had (dl380?) has a SmartArray device that exposes
the 53c1510 device in both RAID and "normal" modes. The difference
is in RAID mode, the smart array driver (IIRC) should claim the
device instead of sym2 driver. Patch below prevents sym2 from
claiming the device when the RAID "daughter board" is attached.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>