firewire: ohci: split page allocation from dma mapping

firewire: ohci: split page allocation from dma mapping

1394 OHCI PCI driver had long been the only user of dma_alloc_pages().
Although tee subsystem recently started using it, they are still a few
users of the infrequently-used function.

In the discussion for dma-mapping function, Jason Gunthorpe shows his
opinion about the design of public API for the function. According to it,
the users provide physical address to the function, then receive DMA
mapping address, regardless of the location of mapping target.

With the above aspects, this commit eliminates the use of
dma_alloc_pages() from this subsystem.

Link: https://lore.kernel.org/lkml/20250905174324.GI616306@nvidia.com/
Link: https://lore.kernel.org/r/20260110013911.19160-8-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>