Name reverse functional association "functional"

The current name "software_version" is not very useful.
The GUI to determine if an image is functional is looking at
/xyz/openbmc_project/software/<image id>/functional.
The GUI could still do the same thing with "software_version"
by looking for
/xyz/openbmc_project/software/<image id>/software_version to
determine if an image is functional, but that feels really wrong.
Part of openbmc/openbmc#2945.

Tested: Built an image with this change, flashed onto a
Witherspoon and verified the "functional" association
worked forward and reverse.
Change-Id: Icdc396e5bb3c627211b14b6340c6e55da2a772ba
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/configure.ac b/configure.ac
index 96cde53..0c95c57 100755
--- a/configure.ac
+++ b/configure.ac
@@ -62,7 +62,7 @@
 AC_DEFINE(ACTIVE_REV_ASSOCIATION, "software_version", [The name of the active's reverse association.])
 
 AC_DEFINE(FUNCTIONAL_FWD_ASSOCIATION, "functional", [The name of the functional forward association.])
-AC_DEFINE(FUNCTIONAL_REV_ASSOCIATION, "software_version", [The functional reverse association.])
+AC_DEFINE(FUNCTIONAL_REV_ASSOCIATION, "functional", [The name of the functional reverse association.])
 
 AC_DEFINE(VERSION_IFACE, "xyz.openbmc_project.Software.Version",
     [The software version manager interface])