boards: amlogic: add Odroid C4 support

Odroid C4 is an Amlogic SM1 device, the board config and board documentation
are adapted from the Odroid-N2 support from the same vendor.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
[narmstrong: fix odroid-c4.rst typos and structure]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Anand Moon <linux.amoon@gmail.com>
diff --git a/doc/board/amlogic/index.rst b/doc/board/amlogic/index.rst
index 3730419..0e2f8c9 100644
--- a/doc/board/amlogic/index.rst
+++ b/doc/board/amlogic/index.rst
@@ -17,7 +17,7 @@
 +===============================+===========+==============+==============+============+============+=============+==============+
 | Boards               		| Odroid-C2 | P212         | Khadas VIM2  | S400       | U200       | Odroid-N2   | SEI610       |
 |				| Nanopi-K2 | Khadas-VIM   | Libretech-PC |	       | SEI510	    | Khadas-VIM3 | Khadas-VIM3L |
-|				| P200	    | LibreTech-CC |	          |	       |            |	          |    	         |
+|				| P200	    | LibreTech-CC |	          |	       |            |	          | Odroid-C4    |
 |				| P201	    | LibreTech-AC |	          |	       |            |             |    	         |
 +-------------------------------+-----------+--------------+--------------+------------+------------+-------------+--------------+
 | UART               		| **Yes**   | **Yes**      | **Yes**      | **Yes**    | **Yes**    | **Yes**     | **Yes**      |
@@ -83,6 +83,7 @@
    libretech-cc
    nanopi-k2
    odroid-c2
+   odroid-c4
    odroid-n2
    p200
    p201