meta-quanta: s6q: Fix syntax in phosphor-watchdog_%.bbappend

The phosphor-watchdog_%.bbappend has a syntax error of colon.

Tested:
built image successfully and solved the warning message.

Signed-off-by: Joseph Fu <joseph.fu@quantatw.com>
Change-Id: If8bd002e6f140c145c56b7bd0964ad415158d619
diff --git a/meta-quanta/meta-s6q/recipes-phosphor/watchdog/phosphor-watchdog_%.bbappend b/meta-quanta/meta-s6q/recipes-phosphor/watchdog/phosphor-watchdog_%.bbappend
index 4c2fe7d..ceeb719 100644
--- a/meta-quanta/meta-s6q/recipes-phosphor/watchdog/phosphor-watchdog_%.bbappend
+++ b/meta-quanta/meta-s6q/recipes-phosphor/watchdog/phosphor-watchdog_%.bbappend
@@ -1,4 +1,4 @@
-FILESEXTRAPATHS:prepend:s6q := ":${THISDIR}/${PN}"
+FILESEXTRAPATHS:prepend:s6q := "${THISDIR}/${PN}:"
 
 SYSTEMD_OVERRIDE:${PN}:remove:s6q = "poweron.conf:phosphor-watchdog@poweron.service.d/poweron.conf"
 SYSTEMD_SERVICE:${PN}:s6q = " phosphor-watchdog.service \