usb: move CONFIG_USB_XHCI to Kconfig with renaming

Move CONFIG_USB_XHCI to defconfig files for all boards, renaming it
into CONFIG_USB_XHCI_HCD.

As commented in the help of "config USB_XHCI" entry, this has been
a TODO for a long time; now CONFIG_USB_XHCI_HCD and CONFIG_USB_XHCI
have been unified in favor of the former.

Note:
Some boards define CONFIG_USB_XHCI in their headers without
CONFIG_USB, which does not meet the "depends on" in Kconfig.
I added CONFIG_USB=y for those boards when converting.
Otherwise, they would fail to build.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/common/usb.c b/common/usb.c
index 8d9efe5..b3ba487 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -1182,7 +1182,7 @@
 	 * with the device. So a get_descriptor will fail before any
 	 * of that is done for XHCI unlike EHCI.
 	 */
-#ifdef CONFIG_USB_XHCI
+#ifdef CONFIG_USB_XHCI_HCD
 	do_read = false;
 #endif
 	err = usb_setup_device(dev, do_read, dev->parent);