rtc: gemini: Augment DT bindings for Faraday

The Gemini RTC is actually a standard IP block from Faraday
Technology called FTRTC010. Rename the bindings, add the
generic compatible string and add definitions for the two
available clocks.

Cc: [e-mail]
Cc: Po-Yu Chuang <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

Documentation/devicetree/bindings/rtc/cortina,gemini.txt

···
-* Cortina Systems Gemini RTC
-
-Gemini SoC real-time clock.
-
-Required properties:
-- compatible : Should be "cortina,gemini-rtc"
-
-Examples:
-
-rtc@45000000 {
-	compatible = "cortina,gemini-rtc";
-	reg = <0x45000000 0x100>;
-	interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
-};

Documentation/devicetree/bindings/rtc/faraday,ftrtc010.txt

···
+* Faraday Technology FTRTC010 Real Time Clock
+
+This RTC appears in for example the Storlink Gemini family of
+SoCs.
+
+Required properties:
+- compatible : Should be one of:
+  "faraday,ftrtc010"
+  "cortina,gemini-rtc", "faraday,ftrtc010"
+
+Optional properties:
+- clocks: when present should contain clock references to the
+  PCLK and EXTCLK clocks. Faraday calls the later CLK1HZ and
+  says the clock should be 1 Hz, but implementers actually seem
+  to choose different clocks here, like Cortina who chose
+  32768 Hz (a typical low-power clock).
+- clock-names: should name the clocks "PCLK" and "EXTCLK"
+  respectively.
+
+Examples:
+
+rtc@45000000 {
+	compatible = "cortina,gemini-rtc";
+	reg = <0x45000000 0x100>;
+	interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&foo 0>, <&foo 1>;
+	clock-names = "PCLK", "EXTCLK";
+};