driver: clk: Add support for clocks on Armada 37xx

The drivers are based on Linux driver by Gregory Clement.

The TBG clocks support only the .get_rate method.
  - since setting rate is not supported, the driver computes the rates
    when probing and so subsequent calls to the .get_rate method do not
    read the corresponding registers again

The peripheral clocks support methods .get_rate, .enable and .disable.

  - the .set_parent method theoretically could be supported on some clocks
    (the parent would have to be one of the TBG clocks)

  - the .set_rate method would have to try all the divider values to find
    the best approximation of a given rate, and it doesn't seem like
    this should be needed in U-Boot, therefore not implemented

Signed-off-by: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/armada-37xx.dtsi b/arch/arm/dts/armada-37xx.dtsi
index 040e856..c72fd25 100644
--- a/arch/arm/dts/armada-37xx.dtsi
+++ b/arch/arm/dts/armada-37xx.dtsi
@@ -107,6 +107,26 @@
 				status = "disabled";
 			};
 
+			nb_periph_clk: nb-periph-clk@13000 {
+				compatible = "marvell,armada-3700-periph-clock-nb";
+				reg = <0x13000 0x100>;
+				clocks = <&tbg 0>, <&tbg 1>, <&tbg 2>, <&tbg 3>;
+				#clock-cells = <1>;
+			};
+
+			sb_periph_clk: sb-periph-clk@18000 {
+				compatible = "marvell,armada-3700-periph-clock-sb";
+				reg = <0x18000 0x100>;
+				clocks = <&tbg 0>, <&tbg 1>, <&tbg 2>, <&tbg 3>;
+				#clock-cells = <1>;
+			};
+
+			tbg: tbg@13200 {
+				compatible = "marvell,armada-3700-tbg-clock";
+				reg = <0x13200 0x100>;
+				#clock-cells = <1>;
+			};
+
 			pinctrl_nb: pinctrl-nb@13800 {
 				compatible = "marvell,armada3710-nb-pinctrl",
 				"syscon", "simple-mfd";