Delete roc::Program::hsaDevice

Delete roc::Program::hsaDevice and access directly from device
associated with program. This allows to be clear if the device is a
NullDevice which has no meaningful HSA agent backend device.

Change-Id: I81f96aff47bf9b8166d0ff6a5efc7c01f0fb6de3

rocclr/device/rocm/rocprogram.hpp

@@ -57,9 +57,6 @@ class Program : public device::Program {
     return static_cast<const Device&>(device());
   }
 
-  //! Returns the hsaBinary associated with the program
-  hsa_agent_t hsaDevice() const { return rocNullDevice().getBackendDevice(); }
-
   hsa_executable_t hsaExecutable() const {
     assert(!isNull());
     return hsaExecutable_;