dt-bindings: devfreq: rk3399_dmc: improve binding documentation.

dt-bindings: devfreq: rk3399_dmc: improve binding documentation.

There are several typos, references to non existent files, grammar and
punctuation mistakes in the rk3399_dmc.txt binding. This patch tries
to improve the binding documentation and fix these mistakes.

Signed-off-by: Nick Milner <nick.milner@collabora.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
- [1/5] Fix some attributes to match with the code s/_disb/_dis/
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>