drm/amd/display: Fix false BAD_FREE warning from Coverity

This is an attempt to fix false warning raised by Coverity
via multiple CID's.

Addresses-Coverity-ID: 1487412 ("Free of address-of expression")
Cc: Wesley Chalmers <Wesley.Chalmers@amd.com>

Reviewed-by: Wesley Chalmers <wesley.chalmers@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>