dt-bindings: ddr: Add bindings for Samsung LPDDR3 memories

Add compatible for Samsung k3qf2f20db LPDDR3 memory bindings, based on
at25.txt compatible section. Introduce minor fixes in the old
documentation.

Suggested-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Lukasz Luba <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

Documentation/devicetree/bindings/ddr/lpddr3.txt

···
 * LPDDR3 SDRAM memories compliant to JEDEC JESD209-3C
 
 Required properties:
-- compatible : Should be  - "jedec,lpddr3"
+- compatible : Should be "<vendor>,<type>", and generic value "jedec,lpddr3".
+  Example "<vendor>,<type>" values:
+    "samsung,K3QF2F20DB"
+
 - density  : <u32> representing density in Mb (Mega bits)
 - io-width : <u32> representing bus width. Possible values are 8, 16, 32, 64
 - #address-cells: Must be set to 1
···
 Example:
 
 samsung_K3QF2F20DB: lpddr3 {
-	compatible	= "Samsung,K3QF2F20DB", "jedec,lpddr3";
+	compatible	= "samsung,K3QF2F20DB", "jedec,lpddr3";
 	density		= <16384>;
 	io-width	= <32>;
 	#address-cells	= <1>;
···
 
 	timings_samsung_K3QF2F20DB_800mhz: lpddr3-timings@800000000 {
 		compatible	= "jedec,lpddr3-timings";
-		reg		= <800000000>; /* workaround: it shows max-freq */
+		/* workaround: 'reg' shows max-freq */
+		reg		= <800000000>;
 		min-freq	= <100000000>;
 		tRFC		= <65000>;
 		tRRD		= <6000>;