[][kernel][common][eth][Fix issues detected by Coverity scan]

[Description]
Fix issues detected by Coverity scan.

1.mtk_probe: NULL_RETURNS
2.mtk_probe: CERT EXP34-C

[Release-log]
N/A


Change-Id: I5e2c2da3c0f06de08aeac81206ab48cbb9706ce5
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8856903
1 file changed