drm/amdgpu/psp: set autoload support by default

Set psp->autoload_supported to true by default,
as only a few version of ASIC not support autoload,
and the furture version of PSP should support this.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>