phosphor-state-manager: reorder prerm functions

The previous order of all `postinst` functions followed by `prerm`
functions made it easy to miss making a change in the `prerm` due
to their large distances from each other in the file.  Reorder these
so that they are grouped by subpackages rather than function type.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib2be0617f4e1f805ed611688d77bb4d278abbd94