CPU: Tidy up some formatting and a DPRINTF in the simple CPU base class.

CPU: Tidy up some formatting and a DPRINTF in the simple CPU base class.

Put the { on the same line as the if and put a space between the if and the
open paren. Also, use the # format modifier which puts a 0x in front of hex
values automatically. If the ExtMachInst type isn't integral and actually
prints something more complicated, the # falls away harmlessly and we aren't
left with a phantom 0x followed by a bunch of unrelated text.