bhyve: actually call bhyve_caph_cache_catpages

Gcc noticed that bhyve_caph_cache_catpages was defined but unused.
It is a stable/11 copy of caph_cache_catpages in head.

Direct commit to stable/11. This bug does not apply to head.

Reviewed by: grehan
Approved by: markj (mentor)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D12212