This adds support for the Broadcom bcm2711 PCI express controller, found on the Raspberry Pi 4 (aka the bcm2838 SoC). The driver has only been developed against the soldered-on VIA XHCI controller and not tested with other end points. Submitted by: Robert Crowston <crowston_protonmail.com> Differential Revision: https://reviews.freebsd.org/D25068