clk: zynqmp: Fix a memory leak

Fix a memory leak of mux.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/20210818065929.12835-3-shubhrajyoti.datta@xilinx.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>