Update guest input and CAN configuration for QEMU+KVM demo

Update guest input and CAN configuration for QEMU+KVM demo

Changes:
- Tweak agl-qemu-runner to make CAN options configurable.
- Update the IVI guest image agl-qemu-runner configurations to
  enable an emulated PCI CAN device mapped to the host can0.
- Update the IVI guest image agl-qemu-runner configurations to
  change the input device to a USB passthrough corresponding to
  the bottom USB 2.0 connector of the 2x stack on the reference
  hardware, so that a USB touchscreen can be used for demos.

Bug-AGL: SPEC-4618

Change-Id: I3c89dcdc6a7c07e2d161f095eaa28c3a1cb1343b
Signed-off-by: Scott Murray <scott.murray@konsulko.com>