msm: sdhci: Modified version of dynamic pm_qos changes

Improve I/O performance for 8939 based targets.
It support legacy qos framework for all other targets.

This modified pm_qos design improves read/write performance
with minimum impact on power.

Conflicts:
	drivers/mmc/host/sdhci-msm.c
	Documentation/devicetree/bindings/mmc/sdhci-msm.txt

Change-Id: Idca6416d1311e37ccb43e1349d3fa606924a6061
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
Signed-off-by: Bharat Pawar <bpawar@codeaurora.org>
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>