UPSTREAM: dt-bindings: modify document of Rockchip power domains

UPSTREAM: dt-bindings: modify document of Rockchip power domains

Rockchip Socs contain quality of service (qos) blocks managing priority,
bandwidth, etc of the connection of each domain to the interconnect.
These blocks loose state when their domain gets disabled and therefore
need to be saved when disabling and restored when enabling a power-domain.

These qos blocks also are similar over all currently available Rockchip
SoCs.

Change-Id: I03c80e01ae0fd1a66a67db15f24869047862f13f
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
(cherry picked from git.kernel.org mmind/linux-rockchip.git v4.7-armsoc/drivers
 commit 71daabca344b503f98c59e4bdd53a818cd01f2af)