The kernel crashes while resuming from AFTR idle mode. It happens
because L2 cache was not going into retention state.

This patch configures the USE_RETENTION bit of ARM_L2_OPTION register
so that it does not depend on MANUAL_L2RSTDISABLE_CONTROL of
ARM_COMMON_OPTION register for L2RSTDISABLE signal.
Signed-off-by: Inderpal Singh <inderpal.singh@linaro.org>
Tested-by: Chander Kashyap <chander.kashyap@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>