[SCSI] mpt2sas: Don't disable device twice at suspend.

On suspend, _scsih_suspend calls mpt2sas_base_free_resources, which
in turn calls pci_disable_device if the device is enabled prior to
suspending. However, _scsih_suspend also calls pci_disable_device
itself.

Thus, in the event that the device is enabled prior to suspending,
pci_disable_device will be called twice. This patch removes the
duplicate call to pci_disable_device in _scsi_suspend as it is both
unnecessary and results in a kernel oops.

Signed-off-by: Tyler Stachecki <tstache1@binghamton.edu>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>