drivers: net: rmnet_iplo: Initial commit

RmNet IPLO driver will emulate a dummy RmNet physical network device.
This is used for testing and prototyping changes in rmnet_data driver
control and data path. rmnet_iplo will loopback any data which is
passed to it.

CRs-Fixed: 1078373
Change-Id: Iedf9be1e97e047b9cb5d90823209d53fcf4e016f
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>