Add ARC HSDK board support

Add ARC HSDK board support

This changeset adds the necessary files to build
image for Synopsys ARC HS Development Kit (HSDK).
Most of necessary tunnings are stored in meta-synopys layer.

Synopsys DesignWare HSDK (which stands for ARC HS Development Kit)
is the latest and greatest development platform that sports
quad-core ARC HS38 in real silicon.

Most noticeable features of the board are:
* Quad-core ARC HS38 CPU running at 1GHz
* 4Gb of DDR
* Built-in Vivante GPU
* Built-in Wi-Fi/Bluetooth module

Peripherals:
* [micro] SD-card slot
* 2 USB 2.0 ports
* 1Gbit Ethernet port
* Built-in Digilent JTAG probe
* Serial port accessible via micro-USB port

New feature: SPEC-2346

Change-Id: I8772ee51cc3db9f6549da2d6a5ea2d116586cde6
Signed-off-by: Evgeniy Didin <didin@synopsys.com>