clk: rockchip: fix clk_i2sout parent selection bits on rk3399

Register, shift and mask were wrong according to datasheet.

Fixes: 11551005 ("clk: rockchip: add clock controller for the RK3399")
Cc: stable@vger.kernel.org
Signed-off-by: Alberto Panizzo <alberto@amarulasolutions.com>
Signed-off-by: Anthony Brandon <anthony@amarulasolutions.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>