net: velocity: Fixes for new velocity platform code

Correctly configure the ICPLUS IP101A bits.
Use the correct register to read the revision id of the controller.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
net: velocity: Update code to mainline submitted version

Update the local copy of the velocity driver to the current mainline
submitted version (v4) for testing.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>