IB/hfi1: Use kcalloc() in hfi1_user_sdma_alloc_queues()

* Multiplications for the size determination of memory allocations
  indicated that array data structures should be processed.
  Thus reuse the corresponding function "kcalloc".

  This issue was detected by using the Coccinelle software.

* Replace the specification of a data type by a pointer dereference
  to make the corresponding size determination a bit safer according to
  the Linux coding style convention.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Doug Ledford <dledford@redhat.com>