usb: dwc3: core: Fix ULPI PHYs and prevent phy_get/ulpi_init during suspend/resume

In order for ULPI PHYs to work, dwc3_phy_setup() and dwc3_ulpi_init()
must be doene before dwc3_core_get_phy().

commit 541768b0 ("usb: dwc3: core: Call dwc3_core_get_phy() before initializing phys")
broke this.

The other issue is that dwc3_core_get_phy() and dwc3_ulpi_init() should
be called only once during the life cycle of the driver. However,
as dwc3_core_init() is called during system suspend/resume it will
result in multiple calls to dwc3_core_get_phy() and dwc3_ulpi_init()
which is wrong.

Fix this by moving dwc3_ulpi_init() out of dwc3_phy_setup()
into dwc3_core_ulpi_init(). Use a flag 'ulpi_ready' to ensure that
dwc3_core_ulpi_init() is called only once from dwc3_core_init().

Use another flag 'phys_ready' to call dwc3_core_get_phy() only once from
dwc3_core_init().

Fixes: 541768b0 ("usb: dwc3: core: Call dwc3_core_get_phy() before initializing phys")
Fixes: f54edb53 ("usb: dwc3: core: initialize ULPI before trying to get the PHY")
Cc: linux-stable <stable@vger.kernel.org> # >= v4.13
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>