MFC [Hyper-V]: r296028

hyperv: Wait 5 seconds for hyperv result, instead of 500ms

This addresses various devices (network, stoarge) attach failure.

Approved by: re (gjb)
Reported by: Hongxiong Xian <v-hoxian microsoft com>
Tested by: Hongxiong Xian <v-hoxian microsoft com>
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5435