Found and fixed bug in dac_load_data_buffer_dual helper function for STM32 lines.

I found an issue with the helper function that had to do with the register offset on one of the values.

I also made the function arguments 16 bits instead of 32 since the registers are size 12 maximum and anything greater will just get truncated anyway.

I checked the Programmer's Manuals for all the STM32 lines and they are all consistent in the register offset.