mrst/vrtc: Avoid using cmos rtc ops

If we don't assign Moorestown specific wallclock init and ops function
the rtc/persisent clock code will use cmos rtc for access, this will
crash Moorestown in that the ioports are not present.

Also in vrtc driver, should avoid using cmos access to check UIP status.

[feng.tang@intel.com: use set_fixmap_offset_nocache() to simplify code]
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>