Use embedded_hal::blocking::spi::Write instead of FullDuplex

[andy31415]

Issue description

Trying to compile the stm32f0 examples results in an error because embedded_hal::spi::FullDuplex is not implemented for SPI on stm32f0xx_hal:

error[E0277]: the trait bound `Spi<stm32f0xx_hal::pac::SPI1, stm32f0xx_hal::gpio::gpioa::PA5<Alternate<stm32f0xx_hal::gpio::AF0>>, stm32f0xx_hal::gpio::gpioa::PA6<Alternate<stm32f0xx_hal::gpio::AF0>>, stm32f0xx_hal::gpio::gpioa::PA7<Alternate<stm32f0xx_hal::gpio::AF0>>, EightBit>: _embedded_hal_spi_FullDuplex<u8>` is not satisfied
  --> examples/stm32f0_ws2812_spi_blink.rs:54:34
   |
54 |         let mut ws = Ws2812::new(spi);
   |                      ----------- ^^^ the trait `_embedded_hal_spi_FullDuplex<u8>` is not implemented for `Spi<stm32f0xx_hal::pac::SPI1, stm32f0xx_hal::gpio::gpioa::PA5<Alternate<stm32f0xx_hal::gpio::AF0>>, stm32f0xx_hal::gpio::gpioa::PA6<Alternate<stm32f0xx_hal::gpio::AF0>>, stm32f0xx_hal::gpio::gpioa::PA7<Alternate<stm32f0xx_hal::gpio::AF0>>, EightBit>`
   |                      |
   |                      required by a bound introduced by this call
   |
note: required by a bound in `ws2812_spi::Ws2812::<SPI>::new`
  --> /home/andrei/.cargo/registry/src/github.com-1ecc6299db9ec823/ws2812-spi-0.4.0/src/lib.rs:49:10
   |
49 |     SPI: FullDuplex<u8, Error = E>,
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ws2812_spi::Ws2812::<SPI>::new`

However embedded_hal::blocking::spi::Write is implemented. This implementation should be available for all FullDuplex implementations:

https://docs.rs/embedded-hal/latest/embedded_hal/blocking/spi/write/trait.Default.html

Testing

Compiled and ran examples on a STM32F030C8Tx, observed LED examples worked well.
Compiled other targets and observed compilation finished (did not run, however this seems to confirm that Write trait is implemented where previously FullDuplex was provided).

[david-sawatzke]

This isn't a distinction offered by e-h 1.0.0 anymore