usb: convert to partial linking

Looks like this was missed during the conversion to partial linking.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

Makefile

@@ -266,7 +266,7 @@ endif
 LIBS += drivers/rtc/librtc.o
 LIBS += drivers/serial/libserial.o
 LIBS += drivers/twserial/libtws.o
-LIBS += drivers/usb/eth/libusb_eth.a
+LIBS += drivers/usb/eth/libusb_eth.o
 LIBS += drivers/usb/gadget/libusb_gadget.o
 LIBS += drivers/usb/host/libusb_host.o
 LIBS += drivers/usb/musb/libusb_musb.o

drivers/usb/eth/Makefile

@@ -21,7 +21,7 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	:= $(obj)libusb_eth.a
+LIB	:= $(obj)libusb_eth.o
 
 # new USB host ethernet layer dependencies
 COBJS-$(CONFIG_USB_HOST_ETHER) += usb_ether.o
@@ -36,7 +36,7 @@ OBJS	:= $(addprefix $(obj),$(COBJS))
 all:	$(LIB)
 
 $(LIB):	$(obj).depend $(OBJS)
-	$(AR) $(ARFLAGS) $@ $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
 #########################################################################