dt-bindings: clock: ti,sci-clk: Add support for parsing clock info from DT

By default, the available clock info is queried from firmware, which can
be quite a lengthy operation if there is a very large amount of clocks
available. Add option for parsing the used clocks from DT instead, and
only register these which can improve the boot time of the device quite
a lot.

Signed-off-by: Tero Kristo <t-kristo@ti.com>

Documentation/devicetree/bindings/clock/ti,sci-clk.txt

@@ -18,6 +18,13 @@ Required properties:
   and clocks IDs for 66AK2G SoC are documented at
   http://processors.wiki.ti.com/index.php/TISCI#66AK2G02_Data
 
+Optional properties:
+-------------------
+- ti,scan-clocks-from-dt: Scan clock tree info from DT. By default,
+  clocks are queried from firmware, which can be rather slow operation,
+  especially if there is a really large number of clocks available out
+  of which only a handful are ever used by kernel.
+
 Examples:
 --------