meta-facebook: switch '/usr/libexec' to libexecdir

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6263aa9f0c24f53494ffc42d233bf2bd48f0c96a
diff --git a/meta-facebook/recipes-phosphor/gpio/phosphor-gpio-monitor_%.bbappend b/meta-facebook/recipes-phosphor/gpio/phosphor-gpio-monitor_%.bbappend
index cd11f54..398ccf7 100644
--- a/meta-facebook/recipes-phosphor/gpio/phosphor-gpio-monitor_%.bbappend
+++ b/meta-facebook/recipes-phosphor/gpio/phosphor-gpio-monitor_%.bbappend
@@ -23,7 +23,7 @@
     install -m 0644 ${WORKDIR}/obmc-ipmb-rescan-fru.service \
                     ${D}${systemd_system_unitdir}
 
-    install -d ${D}/usr/libexec/phosphor-gpio-monitor
-    install -m 0777 ${WORKDIR}/ipmb-rescan-fru.sh ${D}/usr/libexec/phosphor-gpio-monitor/
+    install -d ${D}${libexecdir}/phosphor-gpio-monitor
+    install -m 0777 ${WORKDIR}/ipmb-rescan-fru.sh ${D}${libexecdir}/phosphor-gpio-monitor/
 }
 FILES:${PN} += "/lib/systemd/system/obmc-ipmb-rescan-fru.service"