ARM: dts: Configure sgx for dra7

I've tested that the interconnect target module enables and idles
just fine when probed with ti-sysc with PM runtime control via sys:

# echo on > $(find /sys -name control | grep \/5600)
# rwmem 0x5600fe00      # OCP Revision
0x5600fe00 = 0x40000000
# echo auto > $(find /sys -name control | grep \/5600)

Cc: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Robert Nelson <robertcnelson@gmail.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>