Add ShellCheck's --enable=all inside cmd/

The only exception is `cmd/vdev_id/vdev_id` which might be a subject of
refactoring (see #12084)

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #12912

cmd/zpool/zpool.d/smart

@@ -69,6 +69,7 @@ if [ "$1" = "-h" ] ; then
         exit
 fi
 
+# shellcheck disable=SC2154
 if [ -b "$VDEV_UPATH" ] && PATH="/usr/sbin:$PATH" command -v smartctl > /dev/null || [ -n "$samples" ] ; then
 	if [ -n "$samples" ] ; then
 		# cat a smartctl output text file instead of running smartctl