usb: host: xhci-dxc3: fix compilation warnings

Fix following warnings encountered with platforms
dra7xx_evm and dra7xx_hs_evm :

       arm:  +   dra7xx_evm
+  hccr = (struct xhci_hccr *)devfdt_get_addr(dev);
+         ^
+  hcor = (struct xhci_hcor *)((phys_addr_t)hccr +
+                              ^
w+drivers/usb/host/xhci-dwc3.c: In function 'xhci_dwc3_probe':
w+drivers/usb/host/xhci-dwc3.c:124:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
w+drivers/usb/host/xhci-dwc3.c:125:30: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
w+drivers/usb/host/xhci-dwc3.c:125:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
       arm:  +   dra7xx_hs_evm
+  hccr = (struct xhci_hccr *)devfdt_get_addr(dev);
+         ^
+  hcor = (struct xhci_hcor *)((phys_addr_t)hccr +
+                              ^
w+drivers/usb/host/xhci-dwc3.c: In function 'xhci_dwc3_probe':
w+drivers/usb/host/xhci-dwc3.c:124:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
w+drivers/usb/host/xhci-dwc3.c:125:30: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
w+drivers/usb/host/xhci-dwc3.c:125:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

Introduced by 7e65e84 usb: host: xhci-dwc3: Convert driver to DM

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>