drm/amdgpu/pm: Check input value for CUSTOM profile mode setting on legacy SOCs

[ Upstream commit df0a9bd9 ]

Check the input value for CUSTOM profile mode setting on legacy
SOCs. Otherwise we may use uninitalized value of input[]

Signed-off-by: Ma Jun <Jun.Ma2@amd.com>
Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>