MFC r334484:
Implement the __sg_alloc_table_from_pages() function based on the existing
sg_alloc_table_from_pages() function in the LinuxKPI.

This basically allow segments to have a limit, max_segment.

Submitted by: Johannes Lundberg <johalun0@gmail.com>
Sponsored by: Mellanox Technologies
Sponsored by: Limelight Networks