CVE-2026-90422

In the Linux kernel, the following vulnerability has been resolved:

clk: mediatek: pllfh: Fix IO remapping leak in register_pllfhs error path

When mtk_clk_register_pllfhs function fails to register a PLL, it unregisters all PLLs and cleans up itself in its error path before returning, so the function callers don't need to do it.

But contrary to mtk_clk_unregister_pllfhs function, that does almost the same sequence, it does not free the IO memory mapped on fhctl node, leading to a leak.

Fix this leak by factorizing the cleanup sequence in a new private function and use it both mtk_clk_register_pllfhs and mtk_clk_unregister_pllfhs functions.

Also, change the loop index start value to avoid the -1 operation on index at each loop.