mhi: devices: satellite driver initial feature

MHI proxy satellite device driver enables NON-HLOS MHI satellite
drivers to communicate with device over PCIe link without host
involvement. Host facilitates propagation of events from device
to NON-HLOS MHI satellite drivers, channel states, and power
management over IPC communication. It helps in HLOS power
savings.

CRs-Fixed: 2361053
Change-Id: Ic9b39e901cbb7a85c39dda1eacb377c9c615c75d
Acked-by: Bhaumik Vasav Bhatt <bbhatt@qti.qualcomm.com>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>
Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Tony Truong <truong@codeaurora.org>