Synopsys DesignWare ARC SDP boards sport ARC SDP display
controller attached to ADV7511 HDMI encoder.

That change adds desctiption of both ARC PGU and ADV7511 in
ARC SDP'd base-board Device Tree.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: devicetree@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org