Add option for L3 request without retry on failure

This allows to attempt an orderly shutdown via L3 request while avoiding
excessive delay in the failure case (up to 6 seconds with the currently
hard-coded 3 attempts).
--- a/src/g997/drv_dsl_cpe_api_g997_vrx.c
+++ b/src/g997/drv_dsl_cpe_api_g997_vrx.c
@@ -1053,6 +1053,7 @@ DSL_Error_t DSL_DRV_DEV_G997_PowerManage
 {
    DSL_Error_t nErrCode = DSL_SUCCESS, nRet = DSL_SUCCESS;
    DSL_int_t nAttempt = 0, i = 0;
+   DSL_int_t nAttemptCount = DSL_LX_TO_L3_ATTEMPT_COUNT;
    const DSL_int_t nMaxRetry = DSL_LX_TO_L3_TIMEOUT/DSL_L3_WAIT_INTERVAL;
    DSL_G997_PowerManagementStatusData_t PmStatus = {DSL_G997_PMS_NA};
    DSL_VRX_L3RequestStatus_t L3RequestStatus = DSL_VRX_L3_STATUS_NA;
@@ -1095,11 +1096,15 @@ DSL_Error_t DSL_DRV_DEV_G997_PowerManage
       nErrCode = DSL_ERR_NOT_SUPPORTED_BY_DEVICE;
       break;
 
+   case DSL_G997_PMSF_LX_TO_L3_NO_RETRY:
+      nAttemptCount = 1;
+      fallthrough;
+
    case DSL_G997_PMSF_LX_TO_L3:
       if (PmStatus.nPowerManagementStatus != DSL_G997_PMS_L3)
       {
          /* retry it DSL_LX_TO_L3_ATTEMPT_COUNT times */
-         for (nAttempt = 0; nAttempt < DSL_LX_TO_L3_ATTEMPT_COUNT; nAttempt++)
+         for (nAttempt = 0; nAttempt < nAttemptCount; nAttempt++)
          {
             /* L3 shutdown request*/
             nErrCode = DSL_DRV_VRX_SendMsgShutdownRequest(pContext);
--- a/src/include/drv_dsl_cpe_api_g997.h
+++ b/src/include/drv_dsl_cpe_api_g997.h
@@ -1199,7 +1199,10 @@ typedef enum
    procedure. After reaching the L3 state, the line shall remain in the L3 idle
    state until it is forced into another state through this configuration
    parameter. */
-   DSL_G997_PMSF_LX_TO_L3 = 3
+   DSL_G997_PMSF_LX_TO_L3 = 3,
+   /**
+   Same as above, but does not retry in case of failure. */
+   DSL_G997_PMSF_LX_TO_L3_NO_RETRY = 4
 } DSL_G997_PowerManagementStateForce_t;
 
 /**