fat: Fix corrupt inode flags when remove ATTR_SYS flag

We are clearly missing '~' in fat_ioctl_set_attributes().

Cc: <stable@kernel.org>
Reported-by: NDmitry Dmitriev <dimondmm@yandex.ru>
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

fs/fat/file.c

@@ -102,7 +102,7 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
 		if (attr & ATTR_SYS)
 			inode->i_flags |= S_IMMUTABLE;
 		else
-			inode->i_flags &= S_IMMUTABLE;
+			inode->i_flags &= ~S_IMMUTABLE;
 	}
 
 	fat_save_attrs(inode, attr);