base-files: hotplug-call: exit success when dir is absent

"block mount" invokes "hotplug-call mount".  It emits the following
error when mount is not present

	hotplug-call call failed

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

package/base-files/files/sbin/hotplug-call

@@ -11,8 +11,8 @@ USER=root
 export PATH LOGNAME USER
 export DEVICENAME="${DEVPATH##*/}"
 
-[ \! -z "$1" -a -d /etc/hotplug.d/$1 ] && {
+if [ \! -z "$1" -a -d /etc/hotplug.d/$1 ]; then
 	for script in $(ls /etc/hotplug.d/$1/* 2>&-); do (
 		[ -f $script ] && . $script
 	); done
-}
+fi