ARM: dts: am335x-boneblack: Add names for remaining regulators

Add regulator-name properties for the regulators that don't have them,
allowing the kernel to display the name from the schematic rather than
the name of the regulator on the PMIC in order to improve diagnostics.

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>