ARM: dts: msm: Assign USB supplies for SA6155 and SA6155P

Add regulator references for USB PHY voltage supplies for SA6155
MSM and APQ platforms. Also enable peripheral mode only for the
primary controller for now.

Change-Id: Ic8a0f6ff5375df7853e882e109ab7e030eecc7b4
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>