sf: allocate cache aligned buffers to copy from flash

sf: allocate cache aligned buffers to copy from flash

Use memalign() with ARCH_DMA_MINALIGN to allocate read buffers.
This is required because, flash drivers may use DMA for read operations
and may have to invalidate the buffer before read.

Signed-off-by: Ravi Babu <[email protected]>
Signed-off-by: Vignesh R <[email protected]>
Reviewed-by: Tom Rini <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>
Tested-by: Jagan Teki <[email protected]>