drm/radeon: load the lm63 driver for an lm64 thermal chip.

commit 5dc35532 upstream.

Looks like the lm63 driver supports the lm64 as well.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>