x86: kconfig: Move USB to platform Kconfig

Like other peripheral drivers, move USB related drivers to platform
Kconfig as well.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/baytrail/Kconfig b/arch/x86/cpu/baytrail/Kconfig
index 9f4947d..7ea43b9 100644
--- a/arch/x86/cpu/baytrail/Kconfig
+++ b/arch/x86/cpu/baytrail/Kconfig
@@ -19,6 +19,9 @@
 	imply SCSI
 	imply SPI_FLASH
 	imply SYS_NS16550
+	imply USB
+	imply USB_EHCI_HCD
+	imply USB_XHCI_HCD
 	imply VIDEO_VESA
 
 if INTEL_BAYTRAIL