sunxi: Update DRAM clock for Olimex A20 boards

Originally dram clock was set to 480MHz, but this behaves
unstable. To improve stability the clock is reduced to 384MHz

Signed-off-by: Stefan Mavrodiev <stefan.mavrodiev@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

configs/A20-Olimex-SOM-EVB_defconfig

@@ -2,7 +2,7 @@ CONFIG_ARM=y
 CONFIG_ARCH_SUNXI=y
 CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_MACH_SUN7I=y
-CONFIG_DRAM_CLK=480
+CONFIG_DRAM_CLK=384
 CONFIG_MMC0_CD_PIN="PH1"
 CONFIG_MMC3_CD_PIN="PH0"
 CONFIG_MMC3_PINS="PH"