[HAL][UART] Fix incorrect gState check in HAL_UART_RegisterRxEventCallback/HAL_UART_UnRegisterRxEventCallback to allow user Rx Event Callback registration when a transmit is ongoing

Src/stm32l0xx_hal_uart.c

diff --git a/Src/stm32l0xx_hal_uart.c b/Src/stm32l0xx_hal_uart.c
index 60c5a3c..83eb444 100644
--- a/Src/stm32l0xx_hal_uart.c
+++ b/Src/stm32l0xx_hal_uart.c
@@ -936,10 +936,7 @@
     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;
   }
@@ -950,9 +947,6 @@
     status =  HAL_ERROR;
   }
 
-  /* Release Lock */
-  __HAL_UNLOCK(huart);
-
   return status;
 }
 
@@ -966,10 +960,7 @@
 {
   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  */
   }
@@ -980,8 +971,6 @@
     status =  HAL_ERROR;
   }
 
-  /* Release Lock */
-  __HAL_UNLOCK(huart);
   return status;
 }