gnu: fc-host-tools: Fix fc-loadtool.

* gnu/packages/embedded.scm (fc-host-tools)[arguments]<#:phases>
[patch-installation-paths]: Modify.

gnu/packages/embedded.scm

@@ -1013,6 +1013,8 @@ (define-public fc-host-tools
                             "uptools/atcmd/atinterf.c")
                (("/opt/freecalypso/loadtools")
                 (string-append (assoc-ref outputs "out") "/lib/freecalypso/loadtools"))
+               (("\\$\\{INSTALL_PREFIX\\}/loadtools")
+                (string-append (assoc-ref outputs "out") "/lib/freecalypso/loadtools"))
                (("/opt/freecalypso")
                 (assoc-ref outputs "out")))
              #t)))))