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>

dev: Explicitly specify the endianness for packet accessors.

Generally speaking, the endianness of the data devices provide or
accept is dependent on the device and not the ISA the system
executes. This change makes the devices in dev pick an endianness
rather than using the guest's.

For the ISA bus and the UART, accesses are byte sized and so endianness
doesn't matter. The ISA and PCI busses and the devices which use them
are defined to be little endian.

Change-Id: Ib0aa70f192e1d6f3b886d9f3ad41ae03bddb583f
Reviewed-on: https://gem5-review.googlesource.com/c/13462
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

dev-arm: Fix the address range for some I/O devices

Previously, many devices were incorrecty configured to respond to an
address range of size 0xfff. This changes fixes this and sets it to
0x1000.

Change-Id: I4b027a27adf60ceae4859e287d7f34443b398752
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11116
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

dev: Add missing SConscript in src/dev/i2c

dev: Move i2c functionality to src/dev/i2c/