O2EM LFSR Sound Fix

[bataais]

Fix for this, adapted from mess/mame i8244.c:

O2EM generate pseudo-random 1-bit noise using C rand()%2 calls, while real hardware use linear input feed back from it's 24 bit shift register (LFSR) .

Additionally, O2EM only output sound to audio buffer, but forget to rewrite shifted values to odyssey 24 bit shift register.

https://sourceforge.net/p/o2em/bugs/5/#f795