Move serial handling from serprog.c to serial.c

This is the first step in enabling platform independent serprog and it
also allows other drivers to use serial port functionality without
requiring serprog.

Pure code move, no code changed.

Corresponding to flashrom svn r771.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
diff --git a/Makefile b/Makefile
index fbe9f0b..e12b7ac 100644
--- a/Makefile
+++ b/Makefile
@@ -138,6 +138,10 @@
 OBJS += drkaiser.o
 endif
 
+ifeq ($(CONFIG_SERPROG), yes)
+OBJS += serial.o
+endif
+
 ifeq ($(CONFIG_PRINT_WIKI), yes)
 FEATURE_CFLAGS += -D'PRINT_WIKI_SUPPORT=1'
 OBJS += print_wiki.o