remove pci_dma_* abuses and workarounds V2

[Christoph Hellwig]

Back before the dawn of time pci_dma_* with a NULL pci_dev argument
was used for all kinds of things, e.g. dma mapping for non-PCI
devices.  All this has been long removed, but it turns out we
still care for a NULL pci_dev in the wrappers, and we still have
two odd USB drivers that use pci_dma_alloc_consistent for allocating
memory while ignoring the dma_addr_t entirely, and a network driver
mixing the already wrong usage of dma_* with a NULL device with a
single call to pci_free_consistent.

This series switches the two usb drivers to use plain kzalloc, the
net driver to properly use the dma API and then removes the handling
of the NULL pci_dev in the pci_dma_* wrappers.

Changes since V1:
 - remove allocation failure printks
 - use kcalloc
 - fix tsi108_eth
 - improve changelogs