microblaze_boot: Dont hack the elf entry point.

There was some modulo logic to ensure that Microblaze always booted into
physical RAM regardless of the elf entry. Removed it, as QEMU should fail
gracefully when given a bad elf, rather than attempt to run it.

Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
microblaze_boot: Add opaque to machine_cpu_reset()

Allows machine models to define opaque data for the machine_cpu_reset().

Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>