Revert "bhyve: Map the MSI-X table unconditionally for passthrough"

This reverts commit 382eec24c0284bd7dc5997b85abc9ee70ea704a1.

This change causes a regression where a VM using passthrough no longer
starts. Until this is resolved, revert the commit.

Reported by: Raúl Muñoz <raul.munoz@custos.es>