geneve-map-rename: rename geneve-map to tlv-map.

geneve-map-rename: rename geneve-map to tlv-map.

This patch renames the command name related with geneve-map to a more
generic name as following:
add-geneve-map -> add-tlv-map
del-geneve-map -> del-tlv-map
dump-geneve-map -> dump-tlv-map

It also renames the Geneve_table to tlv_table.

By doing this renaming, the NSH variable context header (the same TLV
format as Geneve) or other protocol can reuse the field tun_metadata<N>
in the future.

Signed-off-by: Mengke Liu <mengke.liu@intel.com>
Signed-off-by: Ricky Li <ricky.li@intel.com>
Signed-off-by: Jesse Gross <jesse@kernel.org>