HAL_ETH_Transmit_IT() and HAL_ETH_Transmit() do not set HAL_ETH_STATE_BUSY before modifying TX descriptors creating race-condition

[KarstenHohmeier]

HAL_ETH_Transmit_IT() and HAL_ETH_Transmit() both test gState but do not set it to HAL_ETH_STATE_BUSY before operating on the TX descriptors inside ETH_Prepare_Tx_Descriptors(). This creates a race-condition among themselves and among each other when used concurrently from multiple threads (e.g. preemption under FreeRTOS).

Also Test-and-Set of gState needs to be done atomically (see #70).

https://github.com/STMicroelectronics/stm32h7xx_hal_driver/blob/ceda3ceeca2ee77a76d2de2ee6b560ad87c90a48/Src/stm32h7xx_hal_eth.c#L1002-L1009

Expected was at minimum a Test-and-Set like this:

https://github.com/STMicroelectronics/stm32h7xx_hal_driver/blob/ceda3ceeca2ee77a76d2de2ee6b560ad87c90a48/Src/stm32h7xx_hal_eth.c#L719-L721

[ASEHSTM]

ST Internal Reference: 191088