Added U(S)ART DMA traits for HAL serial types

[HelloWorldTeraByte]

DMA traits for the HAL serial type were missing for some of the U(S)ARTs. The trait was only implemented for the PAC in some places.

The users can now for example use.

let dma1 = StreamsTuple::new(cx.device.DMA1);

let uart_dma_cfg = DmaConfig::default().transfer_complete_interrupt(true).memory_increment(true);

let (tx, rx) = Serial::new(
    cx.device.UART4,
    (tx_pin, rx_pin),
    serial::Config::default()
        .baudrate(9600.bps())
        .wordlength_8()
        .parity_none()
        .stopbits(serial::config::StopBits::STOP1)
        .dma(serial::config::DmaConfig::Rx),
    &clocks,
)
.unwrap()
.split();

let mut dma_rx_transfer = Transfer::init_peripheral_to_memory(
    dma1.2,
    rx,
    cx.local.rx_buf0,
    None,
    uart_dma_cfg,
);

Without the pull request, the users would get DMASet<..> not implemented error for some the U(S)ARTs.

[burrbull]

Note in CHANGELOG.md please

[HelloWorldTeraByte]

This is my first pull request here. Do I add it under the unreleased header?

[burrbull]

yes

[HelloWorldTeraByte]

Done.

[burrbull]

bors r+

[bors]

Build succeeded:

• ci (stm32f401, stable)
• ci (stm32f405, stable)
• ci (stm32f407, stable)
• ci (stm32f410, stable)
• ci (stm32f411, stable)
• ci (stm32f412, stable)
• ci (stm32f413, stable)
• ci (stm32f415, stable)
• ci (stm32f417, stable)
• ci (stm32f423, stable)
• ci (stm32f427, stable)
• ci (stm32f429, stable)
• ci (stm32f437, stable)
• ci (stm32f439, stable)
• ci (stm32f446, stable)
• ci (stm32f469, stable)
• ci (stm32f479, stable)
• Rustfmt