ARM: dts: msm: Update regulators for USB on QM215

QM215 uses the regulators from PM8916. Update the
regulators accordingly to support USB on QM215.
The VDD for USB PHY is supplied by an always ON
embedded regulator and cannot be voted.
So, use a dummy regulator so as to prevent
probe failures.

Change-Id: Ic882379b21f2ae7ddd2e1fc2eb703b097f2e536a
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>