Get rid of useless/confusing subshell

Get rid of useless/confusing subshell

Other function, same stuff like r1.1210 except here there `>/dev/null 2>&1'
hammer is required to silence the ls(1) test.

The make_dev() call is no longer silenced now but does not print on stdout
anyway;  if making the device fails we'd like to know.

Otherwise if probing the disk fails it continues to be silenced.

(cvs diff -w -U1)
	|@@ -2311,3 +2311,2 @@ is_rootdisk() {
	|
	|-	(
	| 		make_dev $_d
	|@@ -2322,6 +2321,6 @@ is_rootdisk() {
	| 			umount /mnt
	|-		fi
	|+	fi >/dev/null 2>&1
	| 		rm -f /dev/{r,}$_d?
	|+
	| 		return $_rc
	|-	) >/dev/null 2>&1
	| }

OK halex