ARM: footbridge: remove custom DMA address handling

Footbridge is the last Arm platform that has its own
__virt_to_bus()/__bus_to_virt()/phys_to_dma()/dma_to_phys() abstraction,
but this is just a simple offset now.

For PCI devices, the offset that is programmed into the PCI bridge must
also be set in each device using dma_direct_set_offset(). As Arm does
not have a pcibios_bus_add_device() helper yet, just use a bus notifier
for this.

For the ISA DMA, drivers now pass a non-translated physical address into
set_dma_addr(), so they have to be converted back with the corresponding
isa_bus_to_virt() function and then into the correct bus address with
the offset using the isa_dma_dev.

Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

ARM: footbridge: move isa-dma support into footbridge

The dma-isa.c was shared between footbridge and shark a long time ago,
but as shark was removed, it can be made footbridge specific again.

The fb_dma bits in turn are not used at all and can be removed.

All the ISA related files are now built into the platform regardless
of CONFIG_ISA, as they just refer to on-chip devices rather than actual
ISA cards.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>