clk: rockchip: fix clock gate for rk3188 spdif_pre

In rk3188 clock branches, spdif_pre gate was set to RK2928_CLKGATE_CON(13) bit 13.
This appears to be a copy-paste error because such a register does not exist.
We correct it to RK2928_CLKGATE_CON(0) and find out that the rk3188 spdif clock
is the same as the rk3066 spdif clock, so we move it to the common clock branches.

Signed-off-by: Julien CHAUVEAU <julien.chauveau@neo-technologies.fr>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>