Delete i2c cmd_mux semaphore more cleanly

[dhalbert]

Adding this xSemaphoreGive(p_i2c->cmd_mux) or removing the xSemaphoreTake(p_i2c->cmd_mux, portMAX_DELAY) prevents this crash:

import board,busio

i2c = busio.I2C(board.SCL, board.SDA)
i2c.deinit()

import wifi

Fixing this also depends on other changes in CircuitPython, reverting the i2c driver managment back to i2c_driver_install() and i2c_driver_delete(), and not trying to keep the instances around.

[tannewt]

Thanks!

[dhalbert]

Despite the fact that this change seems to fix the problem, I'm suspicious of this because the original code is not inherently wrong, it appears. So this may just be avoiding some other bug elsewhere. I inquired about the idiom in the FreeRTOS forums: https://forums.freertos.org/t/vsemaphoredelete-immediately-after-xsemaphoretake/11956/4.