drm/amdgpu: Added missing prototype

Kernel test robot throws below warning ->

>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c:125:5: warning:
>> no previous prototype for 'kgd_arcturus_hqd_sdma_load'
>> [-Wmissing-prototypes]
     125 | int kgd_arcturus_hqd_sdma_load(struct kgd_dev *kgd, void
*mqd,

>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c:195:5: warning:
>> no previous prototype for 'kgd_arcturus_hqd_sdma_dump'
>> [-Wmissing-prototypes]
     195 | int kgd_arcturus_hqd_sdma_dump(struct kgd_dev *kgd,

>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c:227:6: warning:
>> no previous prototype for 'kgd_arcturus_hqd_sdma_is_occupied'
>> [-Wmissing-prototypes]
     227 | bool kgd_arcturus_hqd_sdma_is_occupied(struct kgd_dev *kgd,
void *mqd)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c:246:5: warning:
>> no previous prototype for 'kgd_arcturus_hqd_sdma_destroy'
>> [-Wmissing-prototypes]
     246 | int kgd_arcturus_hqd_sdma_destroy(struct kgd_dev *kgd, void
*mqd,
         |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Added prototype for these functions.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>