drm/amdgpu: Replace invalid device ID with a valid device ID

Initializes Powertune data for a specific Hawaii card by fixing what
looks like a typo in the code. The device ID 66B1 is not a supported
device ID for this driver, and is not mentioned elsewhere. 67B1 is a
valid device ID, and is a Hawaii Pro GPU.

I have tested on my R9 390 which has device ID 67B1, and it works
fine without problems.

Signed-off-by: Sandeep Raghuraman <sandy.8925@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org