There are several occurrances of the pointer hwmgr being dereferenced
before it is null checked.  Fix these by performing the dereference
of hwmgr after it has been null checked.

Addresses-Coverity: ("Dereference before null check")
Fixes: c9ffa427 ("drm/amd/powerplay: enable pp one vf mode for vega10")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>