Some mandatory device info fields like manufacturer can be empty string
when returned from TEE on devices which have not been provisioned with
attestation IDs.
The extraction tool also needs to check for empty string in the
response, and if so, populates the field with Android property values.
Test: extracting device info from new Pixel EVT 1.1 and uploading
Bug: 276958001
Change-Id: I6e1b3dee8ffcd991335bc50b59a0c80f030cdc79
65f50d4662