odroid: dts: change the buck8 min-microvolt value

Change the buck8's min-microvolt to 750000.
Whent thor protocol is used, board_usb_init() should be tried to set to
750000. But it was returned -EINVAL, because '750000' too lower than
2850000. (thor command doesn't work fine because of this problem.)

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

arch/arm/dts/exynos4412-odroid.dts

@@ -213,7 +213,7 @@
 
 				buck8_reg: BUCK8 {
 					regulator-name = "VCC_P3V3_2.85V";
-					regulator-min-microvolt = <2850000>;
+					regulator-min-microvolt = <750000>;
 					regulator-max-microvolt = <3300000>;
 				};
 			};