vmrun.sh: mention new edk2 package

uefi-edk2-bhyve no longer exists.

Reviewed by: markj
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39937

(cherry picked from commit 0ebc92bf3db1685fbcd023e42b683f4b10464095)