Don't apply address and cd register changes to the 'live' registers until pending flag is cleared, but do preserve the upper address bits in the latch. Fixes regression in Overdrive 2 while preserving fix to Mona in 344 bytes

void svp_prog_read_16(svp_context *context)
{
	uint16_t address = context->scratch1 >> 1;
	context->scratch1 = context->rom[address];
}