oxfw: add condition for PLUG SIGNAL FORMAT command

With tester's help, some devices don't have oPCR. This means that AV/C OUTPUT
PLUG SIGNAL FORMAT command is failed for the devices.
oxfw: delete 176.4 kHz support

According to datasheet, this rate is not supported.
firewire-lib: make 'amdtp_stream_wait_callback()' inline function

In post commit, a parameter is given for timeout. So this function
can be inline.