Documentation: Remove device connection documentation

The API that allowed device connection descriptions to
be added is now removed, so removing also the documentation
for it.

Signed-off-by: Heikki Krogerus <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/driver-api/device_connection.rst

···
-==================
-Device connections
-==================
-
-Introduction
-------------
-
-Devices often have connections to other devices that are outside of the direct
-child/parent relationship. A serial or network communication controller, which
-could be a PCI device, may need to be able to get a reference to its PHY
-component, which could be attached for example to the I2C bus. Some device
-drivers need to be able to control the clocks or the GPIOs for their devices,
-and so on.
-
-Device connections are generic descriptions of any type of connection between
-two separate devices.
-
-Device connections alone do not create a dependency between the two devices.
-They are only descriptions which are not tied to either of the devices directly.
-A dependency between the two devices exists only if one of the two endpoint
-devices requests a reference to the other. The descriptions themselves can be
-defined in firmware (not yet supported) or they can be built-in.
-
-Usage
------
-
-Device connections should exist before device ``->probe`` callback is called for
-either endpoint device in the description. If the connections are defined in
-firmware, this is not a problem. It should be considered if the connection
-descriptions are "built-in", and need to be added separately.
-
-The connection description consists of the names of the two devices with the
-connection, i.e. the endpoints, and unique identifier for the connection which
-is needed if there are multiple connections between the two devices.
-
-After a description exists, the devices in it can request reference to the other
-endpoint device, or they can request the description itself.
-
-API
----
-
-.. kernel-doc:: drivers/base/devcon.c
-   :functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove

Documentation/driver-api/index.rst

···
    pm/index
    clk
    device-io
-   device_connection
    dma-buf
    device_link
    component