IB/core: Change the type of an ib_dma_alloc_coherent() argument

Change the type of the dma_handle argument from u64 * to dma_addr_t *.
This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>