Revert "NAT: VPP-1531 api cleanup & update"

Revert "NAT: VPP-1531 api cleanup & update"

This reverts commit bed1421b9f1b3643d93384084972337b596aec73.

/vpp/master3/src/plugins/nat/nat_api.c: In function ‘send_nat_worker_details’:
/vpp/master3/src/vppinfra/clib.h:62:33: error: division ‘sizeof (u8 * {aka unsigned char *}) / sizeof (u8 {aka unsigned char})’ does not compute the number of array elements [-Werror=sizeof-pointer-div]
 #define ARRAY_LEN(x) (sizeof (x)/sizeof (x[0]))
                                 ^
/vpp/master3/src/plugins/nat/nat_api.c:205:43: note: in expansion of macro ‘ARRAY_LEN’
   rmp = vl_msg_api_alloc (sizeof (*rmp) + ARRAY_LEN (w->name) - 1);
                                           ^~~~~~~~~

Change-Id: Ie82672c145fb2f6580827f95e535435307bc7a23
Signed-off-by: Ole Troan <ot@cisco.com>