ath10k: make ath10k_pci_read32/write32() ops more generic

ath10k: make ath10k_pci_read32/write32() ops more generic

ath10k_pci_read32/write32() does work more specific to
PCI by ensuring pci wake/sleep for every read and write.
There is a plan to use most of stuff available in pci.c
(irq stuff, copy engine, etc) for AHB case. Such kind
of pci wake/sleep for every read/write is not required
in AHB case (qca4019). All those reusable areas in pci.c
and ce.c calls ath10k_pci_read32/write32() for low level
read and write.

In fact, ath10k_pci_read32/write32() should do what it does
today for PCI case. But for AHB, it has to do differently.
To make ath10k_pci_read32/write32() more generic, new function
pointers are added in ar_pci for the function which does
operation more close to the bus. Later, corresponding bus
specific read and write function will be mapped to that.

ath10k_pci_read32/write32() are changed to call directly
those function pointers without worrying which bus underlying
to it. Also, the function to get number of bank is changed
in the same way.

Signed-off-by: Raja Mani <rmani@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>