fs/jffs2: fix comments mentioning i_mutex

inode->i_mutex has been replaced with inode->i_rwsem long ago. Fix
comments still mentioning i_mutex.

Signed-off-by: hongnanli <hongnan.li@linux.alibaba.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

cpukit/libfs/src/jffs2/src/jffs2_fs_i.h

@@ -18,11 +18,11 @@
 #include <linux/mutex.h>
 
 struct jffs2_inode_info {
-	/* We need an internal mutex similar to inode->i_mutex.
+	/* We need an internal mutex similar to inode->i_rwsem.
 	   Unfortunately, we can't used the existing one, because
 	   either the GC would deadlock, or we'd have to release it
 	   before letting GC proceed. Or we'd have to put ugliness
-	   into the GC code so it didn't attempt to obtain the i_mutex
+	   into the GC code so it didn't attempt to obtain the i_rwsem
 	   for the inode(s) which are already locked */
 	struct mutex sem;