usb: qusb2: De-assert TCSR_QUSB2PHY_CLAMP_DIG_N_1P8 upon boot up

This prevents leakage on 1p8 power rail upon boot up when usb cable
is not connected.

Change-Id: Ia19d54df6086cfb0047fcdd8b04e7e0edff91cf7
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>