drm/nouveau/fb/ramgk104: fix spelling mistake "sucessfully" -> "successfully"

There is a spelling mistake in a nvkm_debug message. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>