s3c24x0: Fix usb_ohci.c missing in Makefile
and usb_ohci.c warning differ in signedness

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/cpu/arm920t/s3c24x0/Makefile b/cpu/arm920t/s3c24x0/Makefile
index 0ff36c5..1ed9bf30 100644
--- a/cpu/arm920t/s3c24x0/Makefile
+++ b/cpu/arm920t/s3c24x0/Makefile
@@ -26,7 +26,7 @@
 LIB	= $(obj)lib$(SOC).a
 
 COBJS	= i2c.o interrupts.o serial.o speed.o \
-	  usb.o
+	  usb.o usb_ohci.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))