Enhancement: Proper i2cbus deinit

[vthakur7f]

Product: (OC-SDR, OC-LTE, OC-LTE, OC-Power, others)

OC-SDR

Component: (PSU, GBC, BBU, FEM, LED, ME)

GBC/FE/SDR

Category: (Hardware, Software/stack, Firmware/bootloader, Documentation)

Firmware/OCWare
Describe the solution you'd like
Clean de-init for I2C bus.

Is your feature request related to a problem? Please describe.
Since we haven't had a true use case to close an i2c bus, our i2c handle store (i2cbus.c) doesn't have the ability to properly de-initialize all the handles that have been opened. We hack around this in all our unit tests right now (Test_pca9557.c, Test_sx1509.c, etc.), but we should probably clean this up.