Merge tag 'arcpgu-updates-2019.07.18' of github.com:abrodkin/linux into drm-next

This is a pretty simple improvement that allows to find encoder
as the one and only (ARC PGU doesn't support more than one) endpoint
instead of using non-standard "encoder-slave" property.

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Link: https://patchwork.freedesktop.org/patch/msgid/CY4PR1201MB0120FDB10A777345F9C27720A1C90@CY4PR1201MB0120.namprd12.prod.outlook.com