For USB ethernet device, it failed by directory existed but the two files (device and vendor) not exited. So now check the two files to ensure the present of Ethernet device.

Also fix a bug that not output of lspci/lsusb was considered as device exists.


Review URL:
(cherry picked from commit 6006f33dc8c9ae955c6ac041d8fe54fb9873aea1)
1 file changed