drm/amdgpu/jpeg2.0: fix no previous prototype for functions

Include header file jpeg_v2_0.h.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>