clk: zynqmp: fix kernel doc

Add missing description of 'custom_type_flag' structure member.

Fixes: e605fa9c ("clk: zynqmp: Add support for custom type flags")
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Link: https://lore.kernel.org/r/1629720433-19019-1-git-send-email-rajan.vaja@xilinx.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/zynqmp/clk-zynqmp.h

@@ -56,6 +56,7 @@ enum topology_type {
  * @type:	Type of topology
  * @flag:	Topology flags
  * @type_flag:	Topology type specific flag
+ * @custom_type_flag: Topology type specific custom flag
  */
 struct clock_topology {
 	u32 type;