Move simple firmware related queries into HardwareInterface.

This change moves the following functions from utils to
HardwareInterface:
    GetHardwareClass()
    GetFirmwareVersion()
    GetECVersion()

BUG=None
TEST=unit tests

Change-Id: I20047a3fac8cca3c36730fef305751e6da3c2bb5
Reviewed-on: https://chromium-review.googlesource.com/174930
Commit-Queue: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
diff --git a/hardware.h b/hardware.h
index cbf8aee..7f895c9 100644
--- a/hardware.h
+++ b/hardware.h
@@ -18,6 +18,9 @@
 
   // HardwareInterface methods.
   virtual const std::string BootDevice();
+  virtual std::string GetHardwareClass();
+  virtual std::string GetFirmwareVersion();
+  virtual std::string GetECVersion();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Hardware);