[][Fix switch converity issue]

[Description]
Fix switch converity issue.
1: Check the error status of function call fgets.
2: Fix the file so that both jaguar dsa and gsw recognize embedded switch.

[Release-log]
N/A

Change-Id: Icbefcecf694f4ca1f18a39d2bf0dd7524c3f3de7
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6329527
1 file changed