drm/radeon: fix ATPX function documentation

Fix a copy&pasted documentation.
Signed-off-by: NIgor Murzov <e-mail@date.by>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_atpx_handler.c

@@ -352,9 +352,9 @@ static int radeon_atpx_switchto(enum vga_switcheroo_client_id id)
 }
 
 /**
- * radeon_atpx_switchto - switch to the requested GPU
+ * radeon_atpx_power_state - power down/up the requested GPU
  *
- * @id: GPU to switch to
+ * @id: GPU to power down/up
  * @state: requested power state (0 = off, 1 = on)
  *
  * Execute the necessary ATPX function to power down/up the discrete GPU