OvmfPkg/PvScsiDxe: Open PciIo protocol for later use

This will give us an exclusive access to the PciIo of this device
after it was started and until it will be stopped.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2567
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Message-Id: <20200328200100.60786-9-liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>

OvmfPkg/PvScsiDxe/PvScsi.h

@@ -19,6 +19,7 @@
 
 typedef struct {
   UINT32                          Signature;
+  EFI_PCI_IO_PROTOCOL             *PciIo;
   UINT8                           MaxTarget;
   UINT8                           MaxLun;
   EFI_EXT_SCSI_PASS_THRU_PROTOCOL PassThru;