ath10k: snoc: stop including pci.h

It's easier to violate abstractions and introduce bugs when snoc.h is
including pci.h. Let's not do that.

I'm not extremely familiar with this driver yet, but several of the
shared PCI/SNOC bits seem to be related to the Copy Engine, so move them
to ce.h.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>