sunxi: OLinuXino Lime A20 boards: Use 384 MHz DRAM clock

sunxi: OLinuXino Lime A20 boards: Use 384 MHz DRAM clock

We have a number of OlinuXino Lime2 boards (both NAND and eMMC versions)
which were experiencing sporadic hangs. After testing with some heavy
benchmarking and help from the Armbian forum, it was pinned down as the
DRAM settings for the board. The default is 480MHz, but this is unstable,
and even the build instructions from the vendor Olimex themselves say to
set the DRAM clock to 384. See line 96 at:
https://github.com/OLIMEX/OLINUXINO/blob/master/SOFTWARE/A20/A20-build-3.4.103-release-2/BUILD_DESCRIPTION_A20_Olimex_kernel_3.4.103%2B_Jessie_rel_2.txt

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>