MFC r357509-r357510: small psm cleanup

r357509:
psm: release resources on attach failure

In exactly 1/3 cases we'll release resources on failure; touch up the other
two to do so as well.

r357510:
psm: use make_dev_s instead of make_dev

This most importantly reduces duplication, but it also removes any potential
race with usage of dev->si_drv1 since it's now set prior to the device being
constructed enough to be accessible.