misc: mic: SCIF memory registration and unregistration

This patch implements the SCIF APIs required to pin and unpin
pages. SCIF registration locks down the pages. It then sends a remote
window allocation request to the peer. Once the peer has allocated
memory, the local SCIF endpoint copies the pinned page information to
the peer and notifies the peer once the copy has complete. The peer
upon receipt of the registration notification adds the new remote
window to its list. At this point the window page information is
available on both self and remote nodes so that they can start
performing SCIF DMAs, CPU copies and fences. The unregistration API
tears down the registration at both self and remote nodes.

Reviewed-by: Nikhil Rao <[email protected]>
Reviewed-by: Ashutosh Dixit <[email protected]>
Signed-off-by: Sudeep Dutt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: sudeepdutt