asmc: move the sysctl registration loops next to their tables

[seuros]

Summary

asmc_attach() and asmc_init() had 4 description tables inline,
several hundred lines from the tables they index. Wrapped each loop in a
function defined after its table.

No functional change.

[adrian]

sys/dev/asmc/asmc.c

530

oh i kinda hate this actually. We should make this an snprintf() into a longer buffer so nfan > 9 is handled right.

(but we can do it after this lands; you're just refactoring the existing code here.)