bhyve: Stop calling pci_lintr_request() in the NVMe device model

The device model effectively assumes that MSI-X is enabled (it never
asserts the legacy interrupt), so any guest which relies on being able
to use the legacy PCI interrupt will fail.

The WIP arm64 port does not implement legacy PCI interrupts, but NVMe
emulation is potentially useful there. Simply remove the call.

Reviewed by: corvink, chuck, jhb
Tested by: chuck
MFC after: 1 month
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D40731