This patch adds code to support read-only RTC support for guests
run by partition mode ACRN. It supports RW for CMOS address port 0x70
and RO for CMOS data port 0x71. Reads to CMOS RAM offsets are fetched
by reading CMOS h/w directly and writes to CMOS offsets are discarded.
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>