During reboot of a switch, WRPC tries to print messages like:
Warning: tx not terminated infinite mcr=0x1001500
Warning: tx timestamp never became available
Warning: tx timestamp never became available
Warning: tx not terminated infinite mcr=0x1001500
Warning: tx timestamp never became available
Warning: tx timestamp never became available
Warning: tx timestamp never became available

The pp_printf in network functions caused netconsole_write_string to be called
recursively. This caused hangs of wrpc.

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>