MFC: r260044

Free the MSI again on detach if allocated. Arguably, this code would be
better off living in aac_pci.c, but it doesn't seem worth creating a
aac_pci_detach() and it's also not the first PCI-specific bit in aac.c
MFC: r260045

- Simplify MSI allocation and release. For a single one, we don't need to
  fiddle with the MSI count and pci_release_msi(9) is smart enough to just
  do nothing in case of INTx.
- Don't allocate MSI as RF_SHAREABLE.
MFC: r260050, r261528

- Switch to using the common MII bitbang'ing code instead of duplicating it.
- Based on lessons learnt with dc(4) (see r185750), add bus space barriers to
  the MII bitbang read and write functions as well as to instances of page
  switching.
- Add missing locking to ed_ifmedia_{upd,sts}().
- Canonicalize some messages.
- Based on actual functionality, ED_TC5299J_MII_DIROUT should be rather named
  ED_TC5299J_MII_DIRIN.
- Remove unused headers.
- Use DEVMETHOD_END.
- Use NULL instead of 0 for pointers.