ARM: dts: dra7: Add vbb-supply to cpu and additional voltages

Add a vbb-supply phandle to the cpus node and also add an additional
triplet of voltages for each OPP in the operating-points-v2 table to
make use of the multi regulator support in the OPP core and provide the
vbb regulator for use by the ti-opp-supply driver.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>