Btrfs: fix error message formatting

Make an error msg look nicer by inserting a space between number and word.

Signed-off-by: Hu Tao <hu.taoo@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 file changed