ARM: tegra: colibri_t30: enable emmc ddr52 mode

Add mmc-ddr-1_8v property enabling eMMC DDR52 mode.

root@colibri-t30:~# cat /sys/kernel/debug/mmc1/ios
clock:          52000000 Hz
actual clock:   52000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    8 (mmc DDR52)
signal voltage: 1 (1.80 V)
driver type:    0 (driver type B)
root@colibri-t30:~# hdparm -t /dev/mmcblk1

/dev/mmcblk1:
 Timing buffered disk reads: 222 MB in  3.00 seconds =  73.92 MB/sec
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra30-colibri.dtsi

@@ -933,6 +933,7 @@ sdhci@78000600 {
 		non-removable;
 		vmmc-supply = <&reg_module_3v3>; /* VCC */
 		vqmmc-supply = <&reg_1v8_vio>; /* VCCQ */
+		mmc-ddr-1_8v;
 	};
 
 	/* EHCI instance 1: USB2_DP/N -> AX88772B */