x86: Move common fsp functions into a common file

Some of this file can be shared between FSP1 and FSP2. Move it into a
shared file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/fsp/Makefile b/arch/x86/lib/fsp/Makefile
index e216065..e7a8427 100644
--- a/arch/x86/lib/fsp/Makefile
+++ b/arch/x86/lib/fsp/Makefile
@@ -2,4 +2,5 @@
 #
 # Copyright 2019 Google LLC
 
+obj-y += fsp_common.o
 obj-y += fsp_dram.o