drm/amd/display: fix dereference before NULL check
The "plane_state" pointer was access before checking if it was NULL.
Avoid a possible NULL pointer dereference by accessing the plane
address after the check.
Addresses-Coverity-ID:
1493892 ("Dereference before null check")
Fixes:
3f68c01be9a22 ("drm/amd/display: add cyan_skillfish display support")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>