For STMG4 MCUs, the peripheral registers for DAC have to be accessed by
words (32bits) because DAC is connected to AHB directly.
(This requirement is also there for other MCU series. However, if DAC is
connected to APB like F4/L1/L4 MCUs, AHB byte or half-word transfer is
changed into a 32-bit APB transfer. This means that PSIZE does not have to
be DMA_PDATAALIGN_WORD on these MCUs, and in fact must be BYTE/HALFWORD to
function correctly.)
Fixes issue #9563.
Signed-off-by: Yuuki NAGAO <wf.yn386@gmail.com>