dma-debug: add cacheline to user/kernel space dump messages

Having the cacheline also printed on the debug_dma_dump_mappings() and
dump_show() is useful for debugging. Furthermore, this also standardizes
the messages shown on both dump functions.

Signed-off-by: Desnes Nunes <desnesn@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>