to insert a 0-byte into the Rx stream

 - added UART shutdown req/rsp msg
 - updated location where UART close called so its not called while atomic

was a NULL pointer was getting passed to cfg80211.

Put back commented out CAN drivers

Some kernel incompatibility had to be worked around in order to build
sucessfully for both the wp85 and wp76.

The modules should not be enabled yet because the kernel required to
build the modules is not available yet.

Updated uart driver to return error if file closed vs. WARN_ON
Updated mtwifi init script to kill wpa_supplicant for mt7697

Updated some debug messages in MT7697wifi

There are a number of corner cases which haven't been tested yet.
Specifically, what happens if an IoT card has no eeprom or if it has an
eeprom with invalid content.

The IoT slot driver provides a more modular replacement for the mangoh
driver which is part of the legato framework.  The idea is to separate
out the installation of various sensor devices and the IoT card
framework.

The directory has been placed at linux_kernel_modules/iot_slot/ since
mangoh is an existing driver in this folder.