soc: qcom: stats: Add DDR sleep stats

soc: qcom: stats: Add DDR sleep stats

Add DDR sleep stats that include:

- the available RAM low power states
- per-state residency information
- per-frequency residency information (for some freqs only, it seems)
- DDR vote information (AB/IB)

and some magic thing that we're yet to decode.

Based on the msm-5.4 downstream implementation, debugged with some help
from Qualcomm's Maulik Shah.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20231130-topic-ddr_sleep_stats-v1-2-5981c2e764b6@linaro.org
[bjorn: Add missing bitfield.h include]
Signed-off-by: Bjorn Andersson <andersson@kernel.org>