drm/amdkfd: Fix stack size in 'amdgpu_amdkfd_unmap_hiq'

drm/amdkfd: Fix stack size in 'amdgpu_amdkfd_unmap_hiq'

Dynamically allocate large local variable instead of putting it onto the
stack to avoid exceeding the stack size:
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c: In function ‘amdgpu_amdkfd_unmap_hiq’:
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c:868:1: warning: the frame size of 1280 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307080505.V12qS0oz-lkp@intel.com
Suggested-by: Guchun Chen <guchun.chen@amd.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Acked-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Mukul Joshi <mukul.joshi@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>