[HAL][UART] Fix check on UART Rx state in HAL_UART_RegisterRxEventCallback() and HAL_UART_UnRegisterRxEventCallback() to allow user Rx Event Callback registration when a transmit is ongoing

Src/stm32f0xx_hal_uart.c

diff --git a/Src/stm32f0xx_hal_uart.c b/Src/stm32f0xx_hal_uart.c
index a352509..da48f4d 100644
--- a/Src/stm32f0xx_hal_uart.c
+++ b/Src/stm32f0xx_hal_uart.c
@@ -1002,10 +1002,7 @@
     return HAL_ERROR;
   }
 
-  /* Process locked */
-  __HAL_LOCK(huart);
-
-  if (huart->gState == HAL_UART_STATE_READY)
+  if (huart->RxState == HAL_UART_STATE_READY)
   {
     huart->RxEventCallback = pCallback;
   }
@@ -1016,9 +1013,6 @@
     status =  HAL_ERROR;
   }
 
-  /* Release Lock */
-  __HAL_UNLOCK(huart);
-
   return status;
 }
 
@@ -1032,10 +1026,7 @@
 {
   HAL_StatusTypeDef status = HAL_OK;
 
-  /* Process locked */
-  __HAL_LOCK(huart);
-
-  if (huart->gState == HAL_UART_STATE_READY)
+  if (huart->RxState == HAL_UART_STATE_READY)
   {
     huart->RxEventCallback = HAL_UARTEx_RxEventCallback; /* Legacy weak UART Rx Event Callback  */
   }
@@ -1046,8 +1037,6 @@
     status =  HAL_ERROR;
   }
 
-  /* Release Lock */
-  __HAL_UNLOCK(huart);
   return status;
 }