ks8695: move serial driver to drivers/serial

add CONFIG_KS8695_SERIAL to activate the driver

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/cpu/arm920t/ks8695/Makefile b/cpu/arm920t/ks8695/Makefile
index 7db9473..f6b0063 100644
--- a/cpu/arm920t/ks8695/Makefile
+++ b/cpu/arm920t/ks8695/Makefile
@@ -25,7 +25,7 @@
 
 LIB	= $(obj)lib$(SOC).a
 
-COBJS	= interrupts.o serial.o
+COBJS	= interrupts.o
 SOBJS	= lowlevel_init.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)