mv-ddr-marvell: new package

mv-ddr-marvell: new package

This package adds Marvell Armada SoC DDR training algorithms.
This code is not built separately, it is needed as dependency
to build ATF firmware for Marvell Armada SoCs.

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
[Thomas:
 - Remove MV_DDR_MARVELL_SRC_SYMLINK, ATF will directly pick up the
   mv-ddr-marvell code from where it is.
 - Use "mv-ddr-marvell" as the Config.in prompt, and in the comment
   header of the .mk file.
 - Add upstream URL in Config.in help text
 - Adjust license information.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>