x86: Move table csum into separate file

We need the checksum function without all the other table functionality
soon, so let's split it out into its own C file.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/lib/Makefile b/lib/Makefile
index e3383f4..3842e7d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -73,6 +73,7 @@
 obj-y += membuff.o
 obj-$(CONFIG_REGEX) += slre.o
 obj-y += string.o
+obj-y += tables_csum.o
 obj-y += time.o
 obj-$(CONFIG_TRACE) += trace.o
 obj-$(CONFIG_LIB_UUID) += uuid.o