target: target specific usb initialization

Adds declarations for target specific usb init routines.

Change-Id: I6a7e864f4cc43fa984390be2e085ef314128ff5c
diff --git a/include/target.h b/include/target.h
index c973a61..bb3a6f7 100644
--- a/include/target.h
+++ b/include/target.h
@@ -53,6 +53,10 @@
 bool target_display_panel_node(char *pbuf, uint16_t buf_size);
 uint32_t target_get_boot_device();
 
+const char * target_usb_controller();
+void target_usb_phy_reset(void);
+void target_usb_phy_mux_configure(void);
+
 /* Boot device */
 enum boot_device
 {