clk: rockchip: add dclk_vop_frac ids for rk3399 vop

Export the dclk_vop_frac out, so we can set the dclk_vop as the
child of dclk_vop_frac, and then we can start to take use of
the fractional dividers.

Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

include/dt-bindings/clock/rk3399-cru.h

@@ -138,6 +138,8 @@
 #define DCLK_VOP0_DIV			182
 #define DCLK_VOP1_DIV			183
 #define DCLK_M0_PERILP			184
+#define DCLK_VOP0_FRAC			185
+#define DCLK_VOP1_FRAC			186
 
 #define FCLK_CM0S			190