ARM: dts: imx6q: add 852MHz setpoint for CPU freq

According to datasheet, i.MX6Q has setpoint of 852MHz
which is exclusive with 996MHz, the fuse map of speed_grading
defines the max speed of ARM, here we add this 852MHz
setpoint opp info, kernel will check the speed_grading
fuse and remove all illegal setpoints.
Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6q.dtsi

@@ -30,6 +30,7 @@ cpu@0 {
 				/* kHz    uV */
 				1200000 1275000
 				996000  1250000
+				852000  1250000
 				792000  1150000
 				396000  975000
 			>;
@@ -37,6 +38,7 @@ cpu@0 {
 				/* ARM kHz  SOC-PU uV */
 				1200000 1275000
 				996000	1250000
+				852000	1250000
 				792000	1175000
 				396000	1175000
 			>;