hal: Ensure device_name is copied if empty

For an unknown reason, an msm8960 device name gets empty even
though the value is correct platform side. Fix this copying
again directly if it's empty.

We don't have to worry about checking if it's valid since a check
has been performed before regarding it's validity.

Change-Id: I19e6c6e2a1d445259eb5a519b502d368149dc7fa