ARM: dts: msm: Add new entry for proxy regulator supply

Using the same regulator name to call regulator_get causes
warnings. Instead, add an entry for proxy regulator supply
by renaming the regulator and use that.

Change-Id: Ie20c6da14c70bbccd9fcb4dc602bb38eda918fa5
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>