[OLK-6.6] 使用未初始化变量的编译报错

```
drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c: In function ‘xsc_dcbnl_ieee_setpfc’:

drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c:348:29: warning: ‘curr_pfc_en’ is used uninitialized [-Wuninitialized]

348 |                 curr_pfc_en |= cee_cfg->pfc_setting[i] << i;

|                 ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c:325:12: note: ‘curr_pfc_en’ was declared here

325 |         u8 curr_pfc_en;

|            ^~~~~~~~~~~

drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c: In function ‘xsc_dcbnl_getbuffer.part.0’:

drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c:938:44: warning: ‘buffer’ is used uninitialized [-Wuninitialized]

938 |                 dcb_buffer->prio2buffer[i] = buffer[i];

|                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

drivers/net/ethernet/yunsilicon/xsc/net/xsc_dcbnl.c:922:12: note: ‘buffer’ declared here

922 |         u8 buffer[XSC_MAX_PRIORITY];

|            ^~~~~~
```

GVP openEuler/kernel