arm64: config: enable more USB gadget drivers

arm64: config: enable more USB gadget drivers

This enables all options required to implement the USB protocols that L4T
wishes to expose over the USB flashing port in device mode.

- ACM for serial port access.
- RNDIS for Ethernet access from Windows (or Linux).
- ECM for Ethernet access from MacOS (or Linux).
- Bridge support to bridge the two Ethernet interfaces to a single IP
  address so users don't require different IPs depending on the protocol
  their OS uses. This also simplifies documentation.
- Loop block device support so that the L4T system can also mount the
  filesystem image that is exported over USB Mass Storage.

boot.img size increased by 140384 (T210), 120552 (T186).
(Note: boot.img taken as L4T's Image file, since these are L4T defconfigs)

Bug 1882292

Change-Id: I77cc313dcad505d5d8056c76a55a08a800c676f7
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-on: http://git-master/r/1469845
(cherry picked from commit 0a36077dea7cdedace721b33c38ba9b0c9b69e09 in dev-kernel)
Reviewed-on: http://git-master/r/1484123
GVS: Gerrit_Virtual_Submit
Reviewed-by: Matthew Pedro <mapedro@nvidia.com>
Reviewed-by: Jon Mayo <jmayo@nvidia.com>