`port_settings_apply` does not update tx-eq settings

First noticed debugging #104

If we create a link with port_settings_apply and then attempt to update tx-eq settings on a subsequent call, nothing happens.

Settings do not change for existing link

root@oxz_switch1:~# ./swadm link apply --link qsfp11/0 --tag muffins --speed 100g --fec rs
root@oxz_switch1:~# ./swadm link sd get tx-eq qsfp11/0
           lane 0     lane 1     lane 2     lane 3
pre2      0 (  0)    0 (  0)    0 (  0)    0 (  0)
pre1      0 (  0)    0 (  0)    0 (  0)    0 (  0)
main     26 ( 26)   26 ( 26)   26 ( 26)   26 ( 26)
post1     0 (  0)    0 (  0)    0 (  0)    0 (  0)
post2     0 (  0)    0 (  0)    0 (  0)    0 (  0)
root@oxz_switch1:~# ./swadm link apply --link qsfp11/0 --tag muffins --speed 100g --fec rs --main 7
root@oxz_switch1:~# ./swadm link sd get tx-eq qsfp11/0
           lane 0     lane 1     lane 2     lane 3
pre2      0 (  0)    0 (  0)    0 (  0)    0 (  0)
pre1      0 (  0)    0 (  0)    0 (  0)    0 (  0)
main     26 ( 26)   26 ( 26)   26 ( 26)   26 ( 26)
post1     0 (  0)    0 (  0)    0 (  0)    0 (  0)
post2     0 (  0)    0 (  0)    0 (  0)    0 (  0)

But if you delete the link and create it with a particular tx-eq cursor value from the beginning, that takes

root@oxz_switch1:~# ./swadm link del qsfp11/0
root@oxz_switch1:~# ./swadm link apply --link qsfp11/0 --tag muffins --speed 100g --fec rs --main 7
root@oxz_switch1:~# ./swadm link sd get tx-eq qsfp11/0
           lane 0     lane 1     lane 2     lane 3
pre2      0 (  0)    0 (  0)    0 (  0)    0 (  0)
pre1      0 (  0)    0 (  0)    0 (  0)    0 (  0)
main      7 (  7)    7 (  7)    7 (  7)    7 (  7)
post1     0 (  0)    0 (  0)    0 (  0)    0 (  0)
post2     0 (  0)    0 (  0)    0 (  0)    0 (  0)