drm/radeon/pm: update current crtc info after setting the powerstate

On CI, we need to see if the number of crtcs changes to determine
whether or not we need to upload the mclk table again.  In practice
we don't currently upload the mclk table again after the initial load.
The only reason you would would be to add new states, e.g., for
arbitrary mclk setting which is not currently supported.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org