generic/027: discard mkdir error message

mkdir fails due to ENOSPC occasionally and will fail the whole test.
Redirect stdout and stderr to /dev/null.

Also fix the code style in _cleanup to use single tab.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/027

@@ -36,8 +36,8 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 
 _cleanup()
 {
-    cd /
-    rm -f $tmp.*
+	cd /
+	rm -f $tmp.*
 }
 
 create_file()
@@ -46,7 +46,7 @@ create_file()
 	local direct=$2
 	local i=0
 
-	mkdir -p $dir
+	mkdir -p $dir >/dev/null 2>&1
 	while $XFS_IO_PROG -f $direct -c "pwrite 0 1k" $dir/file_$i >/dev/null 2>&1; do
 		let i=$i+1
 	done