lvm: fix thin recognition

The global var setting was happening in a pipe and did not have an
effect.

Use <<<$() instead.

< <() cannot be used, because dracut is called in chroot's environments,
where /dev/fd does not point to /proc/self/fd, but bash wants
/dev/fd/<num> for this construct.

modules.d/90lvm/module-setup.sh

@@ -57,12 +57,13 @@ install() {
     inst lvm
 
     if [[ $hostonly ]]; then
-        get_host_lvs | while read line; do
+        while read line; do
+            [[ -n "$line" ]] || continue
             printf "%s" " rd.lvm.lv=$line"
             if ! [[ $_needthin ]]; then
                 [[ "$(lvs --noheadings -o segtype ${line%%/*} 2>/dev/null)" == *thin* ]] && _needthin=1
             fi
-        done >> "${initdir}/etc/cmdline.d/90lvm.conf"
+        done <<<$(get_host_lvs) >> "${initdir}/etc/cmdline.d/90lvm.conf"
         echo >> "${initdir}/etc/cmdline.d/90lvm.conf"
     else
         _needthin=1