bus: ti-sysc: Fix a build warning with W=1 for sysconfig

Dhruva reported a build warning with W=1 for "Function parameter or member
'sysconfig' not described in 'sysc'". Let's document sysconfig to fix this.
Reported-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -109,6 +109,7 @@ static const char * const clock_names[SYSC_MAX_CLOCKS] = {
  * @cookie: data used by legacy platform callbacks
  * @name: name if available
  * @revision: interconnect target module revision
+ * @sysconfig: saved sysconfig register value
  * @reserved: target module is reserved and already in use
  * @enabled: sysc runtime enabled status
  * @needs_resume: runtime resume needed on resume from suspend