bhyve: initial PowerCycles value

Currently PowerCycles field of Log Page is 0 and it is an invalid value.
This patch will initial the PowerCycles data to 1.

MFC after: 1 week
Approved by: manu (mentor)
Reviewed By: grehan (older version), chuck, corvink
Differential Revision: https://reviews.freebsd.org/D32558

(cherry picked from commit b631954ff07989b83378bf5cd1af5fad7162c9f9)