all: fix issues found by shellcheck

all: fix issues found by shellcheck

Error: SHELLCHECK_WARNING:
/usr/lib/dracut/dracut-init.sh:939:20: error: Argument to implicit -n is always true due to literal strings. [SC2157]
  937|   dracut_kernel_post() {
  938|       for _f in modules.builtin.bin modules.builtin modules.order; do
  939|->         [[ $srcmods/$_f ]] && inst_simple "$srcmods/$_f" "/lib/modules/$kernel/$_f"
  940|       done
  941|

Error: SHELLCHECK_WARNING:
/usr/lib/dracut/modules.d/98syslog/parse-syslog-opts.sh:18:12: error: This expression is constant. Did you forget a $ somewhere? [SC2078]
   16|       elif [ -e /sbin/syslogd ]; then
   17|           syslogtype="syslogd"
   18|->     elif [ /sbin/syslog-ng ]; then
   19|           syslogtype="syslog-ng"
   20|       else

Error: SHELLCHECK_WARNING:
/usr/lib/dracut/modules.d/90crypt/crypt-lib.sh:15:29: error: Since you double quoted this, it will not word split, and the loop will only run once. [SC2066]
   13|               strstr "$d" "${luks##luks-}" && return 0
   14|               if [ -n "$dev" ]; then
   15|->                 for _dev in "$(devnames $d)"; do
   16|                       [ "$dev" -ef "$_dev" ] && return 0
   17|                   done