sunxi: Add INITIAL_USB_SCAN_DELAY Kconfig option

Some boards have on board usb devices which need longer than the USB
spec's 1 second to connect from board powerup. Add a config option which
when non 0 adds an extra delay before the first usb bus scan.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 464fa0f..fa78720 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -312,6 +312,15 @@
 	slot or emmc on mmc1 - mmc3. Setting this to 1, 2 or 3 will enable
 	support for this.
 
+config INITIAL_USB_SCAN_DELAY
+	int "delay initial usb scan by x ms to allow builtin devices to init"
+	default 0
+	---help---
+	Some boards have on board usb devices which need longer than the
+	USB spec's 1 second to connect from board powerup. Set this config
+	option to a non 0 value to add an extra delay before the first usb
+	bus scan.
+
 config USB0_VBUS_PIN
 	string "Vbus enable pin for usb0 (otg)"
 	default ""