brcmfmac: deal with bus attachments to the module Makefile

As with LinuxKPI-based wireless drivers, e.g., rtw88, PCI depends
on PCI being compiled into the kernel, SDIO will depend on
MMCCAM in the kernel once supported, and USB can always be
loaded.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit 98c44ccb01d9461da477ec8d784c763e4d03fb36)