MLINK mfi.4 to mfi_linux.4 and mfip.4 to cover these kernel modules.

The mfi(4) manpage doesn't explain the modules yet, but at least we direct
users to the right place.

PR:		205925
Submitted by:	dvl
MFC after:	1 week
Sponsored by:	Essen Hackathon 2016

share/man/man4/Makefile

@@ -660,6 +660,8 @@ MLINKS+=lp.4 plip.4
 MLINKS+=malo.4 if_malo.4
 MLINKS+=md.4 vn.4
 MLINKS+=mem.4 kmem.4
+MLINKS+=mfi.4 mfi_linux.4 \
+	mfi.4 mfip.4
 MLINKS+=mlx5en.4 mce.4
 MLINKS+=mn.4 if_mn.4
 MLINKS+=mos.4 if_mos.4