wusb: add debug files for ASL, PZL and DI to the whci-hcd driver

Add asl, pzl and di debugfs files to uwb/uwbN/wusbhc for WHCI host
controller.  These dump the current ASL, PZL and DI buffer.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
diff --git a/drivers/usb/host/whci/Kbuild b/drivers/usb/host/whci/Kbuild
index 26a3871..11e5040 100644
--- a/drivers/usb/host/whci/Kbuild
+++ b/drivers/usb/host/whci/Kbuild
@@ -2,6 +2,7 @@
 
 whci-hcd-y := \
 	asl.o	\
+	debug.o \
 	hcd.o 	\
 	hw.o	\
 	init.o	\