pinctrl: mediatek: free EINT resources on unbind

In the Linux kernel, the following vulnerability has been resolved: pinctrl: mediatek: free EINT resources on unbind mtk_eint_do_init() creates an IRQ domain, populates it with a mapping for every EINT line and installs a chained handler on the parent interrupt, but none of these are ever released. This was harmless while the drivers were built-in, but now that they can be built as modules and unbound/rmmod'd it leaves behind a dangling IRQ domain, interrupt mappings whose chip data points at freed memory, and a chained handler that keeps firing into that freed data. The plain allocations in mtk_eint_do_init() already use the device-managed devm_*() helpers, so tear the remaining resources down the same way: register a devm action that detaches the chained handler, waits for any in-flight handler to finish, disposes of the per-line mappings and removes the IRQ domain. This mirrors the device-managed lifecycle adopted for the GPIO chip and keeps the whole EINT setup self-cleaning on unbind.