staging: erofs: support tracepoint

Add basic tracepoints for ->readpage{,s}, ->lookup,
->destroy_inode, fill_inode and map_blocks.

Reviewed-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>