drm/amdgpu/swsmu: set workload profile to bootup default

Now that we can select a workload profile dynamically when
we submit work, it's best to default to the bootup
default workload profile.  Defaulting to other profiles
prevents some power management features from kicking in
during idle periods.  Once all jobs have finished, the
workload profile will automatically move back to default
bootup for max power savings.

Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>