acpi: Put the version numbers in a central place

At present two acpi files are built every time since they use a version
number from version.h

This is not necessary. Make use of the same technique as for the version
string, so that they are build only when they change.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/version_string.h b/include/version_string.h
index a89a6e4..a7d07e4 100644
--- a/include/version_string.h
+++ b/include/version_string.h
@@ -4,5 +4,7 @@
 #define	__VERSION_STRING_H__
 
 extern const char version_string[];
+extern const unsigned short version_num;
+extern const unsigned char version_num_patch;
 
 #endif	/* __VERSION_STRING_H__ */