clk: imx8mq: Fix sys3 pll references

The "sys3_pll2_out" CLK was removed in refactoring so all references
need to be updated to "sys3_pll_out"

Fixes: e9dda4af ("clk: imx: Refactor entire sccg pll clk")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>