Pineview with DDR3 memory has different latencies to enable CxSR.
This patch updates CxSR latency table to add Pineview DDR3 latency
configuration. It also adds one flag "is_ddr3" for checking DDR3
setting in MCHBAR.

Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: NLi Peng <peng.li@intel.com>
Signed-off-by: NEric Anholt <eric@anholt.net>