Test for changing timing strobe to be internal to the FPGA rather
than internal to the STM. Appears to work fine. Still need to
test with acq_test and normal firmware. Expect a change to
timing_count and timing_strobe calls elsewhere in the code will
be necessary as the counter in the FPGA is clocked at 16.368MHz
whereas the timer in the STM is clocked at 32.736MHz.