usb: dwc3: Disable phy suspend after power-on reset

For DRD controllers, the programming guide recommended that
GUSB3PIPECTL.SUSPENDABLE and GUSB2PHYCFG.SUSPHY to be cleared after
power-on reset and only set after the controller initialization is
completed. This can be done after device soft-reset in dwc3_core_init().
This patch makes sure to clear GUSB3PIPECTL.SUSPENDABLE and
GUSB2PHYCFG.SUSPHY before core initialization and only set them after
the device soft-reset is completed.

Reference: DWC_usb3 3.30a and DWC_usb31 1.90a programming guide section
1.2.49 and 1.2.45

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>