s3c44b0: move serial driver to drivers/serial

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/cpu/s3c44b0/Makefile b/cpu/s3c44b0/Makefile
index 790faeb..fd696f7 100644
--- a/cpu/s3c44b0/Makefile
+++ b/cpu/s3c44b0/Makefile
@@ -26,7 +26,7 @@
 LIB	= $(obj)lib$(CPU).a
 
 START	= start.o
-COBJS	= serial.o interrupts.o cpu.o
+COBJS	= interrupts.o cpu.o
 
 SRCS	:= $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))