drm/radeon: fix typo in golden register setup on evergreen

commit 6abafb78 upstream.

Fixes hangs on driver load on some cards.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=76998



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>