drm/radeon/si: fix define for MC_SEQ_TRAIN_WAKEUP_CNTL

commit d5693761b2b4ff530c8af8af9ec55b6eae76e617 upstream.

Typo in the register offset.

Noticed-by: Sylvain BERTRAND <sylware@legeek.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>