ARM: uniphier: add ProXstream2 and PH1-LD6b support

The DDR SDRAM initialization code has not been mainlined yet, but
U-Boot proper should work.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/doc/README.uniphier b/doc/README.uniphier
index 6792327..6ba0320 100644
--- a/doc/README.uniphier
+++ b/doc/README.uniphier
@@ -48,6 +48,14 @@
     $ make ph1_pro5_defconfig
     $ make CROSS_COMPILE=arm-linux-gnueabi-
 
+ProXstream2:
+    $ make pxs2_defconfig
+    $ make CROSS_COMPILE=arm-linux-gnueabi-
+
+PH1-LD6b:
+    $ make ph1_ld6b_defconfig
+    $ make CROSS_COMPILE=arm-linux-gnueabi-
+
 You may wish to change the "CROSS_COMPILE=arm-linux-gnueabi-"
 to use your favorite compiler.