libexternal: Add support for SPD Information

- SPD: Source product description.
- Retrieve the product vendor and name from the system
  property and pass it to the hdmi driver.
- This will display some specific names for source such
  as instead of "Input 1" it might display "QCOM 8974" for
  example

Change-Id: I5440841b9e47110386c793045f3b30774522dcb6
2 files changed