python: Don't assume SimObjects live in the global namespace

The importer in Python 3 doesn't like the way we import SimObjects
from the global namespace. Convert the existing SimObject declarations
to import from m5.objects. As a side-effect, this makes these files
consistent with configuration files.

Change-Id: I11153502b430822130722839e1fa767b82a027aa
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15981
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>

src/dev/virtio/VirtIO.py

@@ -40,8 +40,8 @@
 from m5.SimObject import SimObject
 from m5.params import *
 from m5.proxy import *
-from Device import PioDevice
-from PciDevice import PciDevice
+from m5.objects.Device import PioDevice
+from m5.objects.PciDevice import PciDevice
 
 
 class VirtIODeviceBase(SimObject):

src/dev/virtio/VirtIO9P.py

@@ -39,7 +39,7 @@
 
 from m5.params import *
 from m5.proxy import *
-from VirtIO import VirtIODeviceBase
+from m5.objects.VirtIO import VirtIODeviceBase
 
 class VirtIO9PBase(VirtIODeviceBase):
     type = 'VirtIO9PBase'

src/dev/virtio/VirtIOBlock.py

@@ -39,7 +39,7 @@
 
 from m5.params import *
 from m5.proxy import *
-from VirtIO import VirtIODeviceBase
+from m5.objects.VirtIO import VirtIODeviceBase
 
 class VirtIOBlock(VirtIODeviceBase):
     type = 'VirtIOBlock'

src/dev/virtio/VirtIOConsole.py

@@ -39,8 +39,8 @@
 
 from m5.params import *
 from m5.proxy import *
-from VirtIO import VirtIODeviceBase
-from Serial import SerialDevice
+from m5.objects.VirtIO import VirtIODeviceBase
+from m5.objects.Serial import SerialDevice
 
 class VirtIOConsole(VirtIODeviceBase):
     type = 'VirtIOConsole'