make: Remove MEMNIC targets from Makefile

These are not currently supported by Intel DPDK vSwitch. Remove until
such a time as they are.

Change-Id: I5ec32493368fe8b851c1f5a4b009b028ab1d429c
Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>
Reviewed-by: Mark D. Gray <mark.d.gray@intel.com>
Reviewed-by: Mark B. Kavanagh <mark.b.kavanagh@intel.com>
Reviewed-by: Ciara Loftus <ciara.loftus@intel.com>