misc: mic: SCIF remote memory map/unmap interface

This patch implements the SCIF mmap/munmap interface. A similar
capability is provided to kernel clients via the
scif_get_pages()/scif_put_pages() APIs. The SCIF mmap interface
queries to check if a window is valid and then remaps the local
virtual address to the remote physical pages. These mappings are
subsequently destroyed upon receipt of the VMA close operation or
scif_get_pages().  This functionality allows SCIF users to directly
access remote memory without any driver interaction once the mappings
are created thereby providing bare-metal PCIe latency. These mappings
are zapped to avoid RMA accesses from user space, if a Coprocessor is
reset.
Reviewed-by: NAshutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: NNikhil Rao <nikhil.rao@intel.com>
Signed-off-by: NSudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>