net: Revert devlink health changes.

This reverts the devlink health changes from 9/17/2019,
Jiri wants things to be designed differently and it was
agreed that the easiest way to do this is start from the
beginning again.

Commits reverted:

cb5ccfbe
880ee82f
c7af343b
ff253fed
6f9d5613
fcd852c6
8a66704a
12bd0dce
aba25279
ce019faa
b8c45a03

And the follow-on build fix:

o33a0efa4baecd689da9474ce0e8b673eb6931c60

Signed-off-by: David S. Miller <davem@davemloft.net>