kernel code test: create_proc_entry is deprecated

This one is replaced by proc_create now.
kernel code test: add a write function in seq_file

Also this patch fix some data length issue.
kernel code test: optimize the pci_bus_get_depth2()
kernel code test: optimize the pci_bus_get_depth2()

Remove unnecessary continue.
kernel code test: optimize on pci_bus_get_depth2

This one looks more beautiful.