Add dummy register support for the cp15, CRn=c15 registers.
config_base_register and power_control_register currently
default to 0, but may have improved support after the QOM
CPU patches are finished.
Signed-off-by: Mark Langsdorf <mark.langsdorf@calxeda.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>