arm64: mm: Remove assembly DMA cache maintenance wrappers

Remove the __dma_{flush,map,unmap}_area assembly wrappers and call the
appropriate cache maintenance functions directly from the DMA mapping
callbacks.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220610151228.4562-3-will@kernel.org


Signed-off-by: Will Deacon <will@kernel.org>