udp: align udp_encap_t_ to 2 cachelines
udp: align udp_encap_t_ to 2 cachelines

Based on the comments in the struct, udp_encap_t_ is meant to span 2
cachelines. Due to the 64 bit alignment of dpo_id_t, the struct spanned
3 cachelines. This caused fetching ue_ip_proto to trigger an additional
cache miss. This patch rearranges the ordering of the struct fields
so that udp_encap_t_ only spans 2 cachelines as intended.

before:
(gdb) print (int)&((struct udp_encap_t_*)0)->cacheline1
$8 = 128

after:
(gdb) print (int)&((struct udp_encap_t_*)0)->cacheline1
$1 = 64

Type: fix
Signed-off-by: Vadym Martsynovskyy <c528bb6a1d4b4b8c330341d8ca75e3a7b057c388@fb.com>
Change-Id: I066c08654d4a8ef3e2d3954e957d4c5d382b209f

chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp