IB/rdmavt: Fix sizeof mismatch

An incorrect sizeof is being used, struct rvt_ibport ** is not correct, it
should be struct rvt_ibport *. Note that since ** is the same size as
* this is not causing any issues.  Improve this fix by using
sizeof(*rdi->ports) as this allows us to not even reference the type
of the pointer.  Also remove line breaks as the entire statement can
fit on one line.

Link: https://lore.kernel.org/r/20201008095204.82683-1-colin.king@canonical.com


Addresses-Coverity: ("Sizeof not portable (SIZEOF_MISMATCH)")
Fixes: ff6acd69 ("IB/rdmavt: Add device structure allocation")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>