[HAL][SPI] Add wait on flag TXE to be set at the end of transaction to be aligned with reference manual

Src/stm32l0xx_hal_spi.c

diff --git a/Src/stm32l0xx_hal_spi.c b/Src/stm32l0xx_hal_spi.c
index 8a966cf..db43fa8 100644
--- a/Src/stm32l0xx_hal_spi.c
+++ b/Src/stm32l0xx_hal_spi.c
@@ -3684,6 +3684,13 @@
   */
 static HAL_StatusTypeDef SPI_EndRxTxTransaction(SPI_HandleTypeDef *hspi, uint32_t Timeout, uint32_t Tickstart)
 {
+  /* Wait until TXE flag */
+  if(SPI_WaitFlagStateUntilTimeout(hspi, SPI_FLAG_TXE, SET, Timeout, Tickstart) != HAL_OK)
+  {
+    SET_BIT(hspi->ErrorCode, HAL_SPI_ERROR_FLAG);
+    return HAL_TIMEOUT;
+  }
+
   /* Timeout in µs */
   __IO uint32_t count = SPI_BSY_FLAG_WORKAROUND_TIMEOUT * (SystemCoreClock / 24U / 1000000U);
   /* Erratasheet: BSY bit may stay high at the end of a data transfer in Slave mode */