drm/amd/powerplay: Fix CZ SMU firmware load check (v4)

Remove an errant return in the middle of the check
function as well as check for success in the start
function.

(v2) Add return check to smu_load_fw()
(v3) Don't return early if SMU load check fails
(v4) No returns!  :-)

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>