eth: phytmac: phytmac_plat_probe: initialize variable 'ret' when !pdata->msg_regs

Fix follow error with clang-19:

drivers/net/ethernet/phytium/phytmac_platform.c:130:8: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
  130 |                         if (!pdata->msg_regs) {
      |                             ^~~~~~~~~~~~~~~~
drivers/net/ethernet/phytium/phytmac_platform.c:202:9: note: uninitialized use occurs here
  202 |         return ret;
      |                ^~~
drivers/net/ethernet/phytium/phytmac_platform.c:130:4: note: remove the 'if' if its condition is always false
  130 |                         if (!pdata->msg_regs) {
      |                         ^~~~~~~~~~~~~~~~~~~~~~~
  131 |                                 dev_err(&pdev->dev, "msg_regs ioremap failed, i=%d\n", i);
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  132 |                                 goto err_mem;
      |                                 ~~~~~~~~~~~~~
  133 |                         }
      |                         ~
drivers/net/ethernet/phytium/phytmac_platform.c:81:9: note: initialize the variable 'ret' to silence this warning
   81 |         int ret, i;
      |                ^
      |                 = 0
1 error generated.

Signed-off-by: WangYuli <wangyuli@uniontech.com>

Author: WangYuli

drivers/net/ethernet/phytium/phytmac_platform.c

@@ -129,6 +129,7 @@ static int phytmac_plat_probe(struct platform_device *pdev)
 			pdata->msg_regs = ioremap_wt(regs->start, MEMORY_SIZE);
 			if (!pdata->msg_regs) {
 				dev_err(&pdev->dev, "msg_regs ioremap failed, i=%d\n", i);
+				ret = PTR_ERR(pdata->mac_regs);
 				goto err_mem;
 			}
 		}