drm/amd/display: Linux hook test pattern through debufs

bug fix: phy test PLTAT is special 80bit test pattern. The 80bit
data should be hard coded within driver so that user does not
need input the deata. previous driver does not have hard coded
80 bits pattern data for PLTPAT. Other than this PLTPAT, user
has to input 80 bits pattern data. In case user input less than
10 bytes data, un-input data byte will be filled by 0x00.

Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>