arm64: Increase ARCH_DMA_MINALIGN to 128

arm64: Increase ARCH_DMA_MINALIGN to 128

This patch increases the ARCH_DMA_MINALIGN to 128 so that it covers the
currently known Cache Writeback Granule (CTR_EL0.CWG) on arm64 and moves
the fallback in cache_line_size() from L1_CACHE_BYTES to this constant.
In addition, it warns (and taints) if the CWG is larger than
ARCH_DMA_MINALIGN as this is not safe with non-coherent DMA.

Cc: Will Deacon <[email protected]>
Cc: Robin Murphy <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>