ARM: dts: Add support for DRA72x family of devices

DRA722 is part of DRA72x family which are single core cortex A15 devices
with most infrastructure IPs otherwise same as whats on the DRA74x family.

So move the cpu nodes into dra74x.dtsi and dra72x.dtsi respectively.

Also add a minimal dra72-evm dts file.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Cc: linux-doc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
[tony@atomide.com: updated for Makefile sorting]
Signed-off-by: Tony Lindgren <tony@atomide.com>