phy: qcom-qusb2: Power-on PHY before initialization

PHY must be powered on before turning ON clocks and
attempting to initialize it. Driver is exposing
separate init and power_on routines for this.
Apparently USB dwc3 core driver performs power-on
after init. Also, poweron and init for QUSB2 PHY
need to be executed together always, hence remove
poweron callback from phy_ops and explicitly perform
this from init, similar changes needed for poweroff.

Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>