usb: USB_XHCI_PCI depends on PCI

Compiling with CONFIG_USB_XHCI_PCI and CONFIG_PCI=n results in

    usb/host/xhci-pci.c:48:(.text.xhci_pci_probe+0x44):
    undefined reference to `dm_pci_write_config32

Add the missing Kconfig dependency.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index b501ea5..35610ff 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -90,7 +90,7 @@
 
 config USB_XHCI_PCI
 	bool "Support for PCI-based xHCI USB controller"
-	depends on DM_USB
+	depends on DM_USB && PCI
 	default y if X86
 	help
 	  Enables support for the PCI-based xHCI controller.