Fixed wrong return value when isr service already installed (GIT8266O-778)

[fherrera124]

When isr service is already installed, calling gpio_install_isr_service(0) must return ESP_ERR_INVALID_STATE, not ESP_FAIL

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}