mvsas: fix panic on expander attached SATA devices

mvsas is giving a General protection fault when it encounters an expander
attached ATA device.  Analysis of mvs_task_prep_ata() shows that the driver is
assuming all ATA devices are locally attached and obtaining the phy mask by
indexing the local phy table (in the HBA structure) with the phy id.  Since
expanders have many more phys than the HBA, this is causing the index into the
HBA phy table to overflow and returning rubbish as the pointer.

mvs_task_prep_ssp() instead does the phy mask using the port properties.
Mirror this in mvs_task_prep_ata() to fix the panic.

Reported-by: Adam Talbot <ajtalbot1@gmail.com>
Tested-by: Adam Talbot <ajtalbot1@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Odin.com>